Java 11 migrate all remaining s (#1120)

* Moves saga to Java 11

* Moves semaphore to Java 11

* Moves servant to Java 11

* Moves serverless to Java 11

* Moves service-layer to Java 11

* Moves service-locator to Java 11

* Moves sharding to Java 11

* Moves singleton to Java 11

* Moves spatial-partition to Java 11

* Moves specification to Java 11

* Moves state to Java 11

* Moves step-builder to Java 11

* Moves strategy to Java 11

* Moves subclass-sandbox to Java 11

* Fixes checkstyle issues

saga/src/main/java/com/iluwatar/saga/choreography/ChoreographyChapter.java

@@ -25,9 +25,9 @@ package com.iluwatar.saga.choreography;
 
 
 /**
- * ChoreographyChapter is an interface representing a contract for an external service.
+ * ChoreographyChapter is an interface representing a contract for an external service. In that
- * In that case, a service needs to make a decision what to do further
+ * case, a service needs to make a decision what to do further hence the server needs to get all
- * hence the server needs to get all context representing {@link Saga}
+ * context representing {@link Saga}
  */
 public interface ChoreographyChapter {
 
@@ -41,6 +41,7 @@ public interface ChoreographyChapter {
 
   /**
    * get name method.
+   *
    * @return service name.
    */
   String getName();

saga/src/main/java/com/iluwatar/saga/choreography/Saga.java

@@ -28,9 +28,8 @@ import java.util.Arrays;
 import java.util.List;
 
 /**
- * Saga representation.
+ * Saga representation. Saga consists of chapters. Every ChoreographyChapter is executed a certain
- * Saga consists of chapters.
+ * service.
- * Every ChoreographyChapter is executed a certain service.
  */
 public class Saga {
 
@@ -61,6 +60,7 @@ public class Saga {
 
   /**
    * add chapter to saga.
+   *
    * @param name chapter name
    * @return this
    */
@@ -71,6 +71,7 @@ public class Saga {
 
   /**
    * set value to last chapter.
+   *
    * @param value invalue
    * @return this
    */
@@ -84,6 +85,7 @@ public class Saga {
 
   /**
    * get value from current chapter.
+   *
    * @return value
    */
   public Object getCurrentValue() {
@@ -92,6 +94,7 @@ public class Saga {
 
   /**
    * set value to current chapter.
+   *
    * @param value to set
    */
   public void setCurrentValue(Object value) {
@@ -100,6 +103,7 @@ public class Saga {
 
   /**
    * set status for current chapter.
+   *
    * @param result to set
    */
   public void setCurrentStatus(ChapterResult result) {
@@ -145,8 +149,8 @@ public class Saga {
   }
 
   /**
-   * Class presents a chapter status and incoming
+   * Class presents a chapter status and incoming parameters(incoming parameter transforms to
-   * parameters(incoming parameter transforms to outcoming parameter).
+   * outcoming parameter).
    */
   public static class Chapter {
     private String name;
@@ -173,6 +177,7 @@ public class Saga {
 
     /**
      * set result.
+     *
      * @param result {@link ChapterResult}
      */
     public void setResult(ChapterResult result) {
@@ -181,6 +186,7 @@ public class Saga {
 
     /**
      * the result for chapter is good.
+     *
      * @return true if is good otherwise bad
      */
     public boolean isSuccess() {

saga/src/main/java/com/iluwatar/saga/choreography/SagaApplication.java

@@ -27,22 +27,19 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * This pattern is used in distributed services to perform a group of operations atomically.
+ * This pattern is used in distributed services to perform a group of operations atomically. This is
- * This is an analog of transaction in a database but in terms
+ * an analog of transaction in a database but in terms of microservices architecture this is
- * of microservices architecture this is executed
+ * executed in a distributed environment
- * in a distributed environment
  *
  * <p>A saga is a sequence of local transactions in a certain context.
- * If one transaction fails for some reason,
+ * If one transaction fails for some reason, the saga executes compensating transactions(rollbacks)
- * the saga executes compensating transactions(rollbacks)
  * to undo the impact of the preceding transactions.
  *
  * <p>In this approach, there are no mediators or orchestrators services.
  * All chapters are handled and moved by services manually.
  *
  * <p>The major difference with choreography saga is an ability to handle crashed services
- * (otherwise in choreography services very hard to prevent a saga
+ * (otherwise in choreography services very hard to prevent a saga if one of them has been crashed)
- * if one of them has been crashed)
  *
  * @see com.iluwatar.saga.choreography.Saga
  * @see Service
@@ -54,10 +51,10 @@ public class SagaApplication {
    * main method.
    */
   public static void main(String[] args) {
-    ServiceDiscoveryService sd = serviceDiscovery();
+    var sd = serviceDiscovery();
-    ChoreographyChapter service = sd.findAny();
+    var service = sd.findAny();
-    Saga goodOrderSaga = service.execute(newSaga("good_order"));
+    var goodOrderSaga = service.execute(newSaga("good_order"));
-    Saga badOrderSaga = service.execute(newSaga("bad_order"));
+    var badOrderSaga = service.execute(newSaga("bad_order"));
     LOGGER.info("orders: goodOrder is {}, badOrder is {}",
         goodOrderSaga.getResult(), badOrderSaga.getResult());
 
@@ -74,7 +71,7 @@ public class SagaApplication {
   }
 
   private static ServiceDiscoveryService serviceDiscovery() {
-    ServiceDiscoveryService sd = new ServiceDiscoveryService();
+    var sd = new ServiceDiscoveryService();
     return sd
         .discover(new OrderService(sd))
         .discover(new FlyBookingService(sd))

saga/src/main/java/com/iluwatar/saga/choreography/Service.java

@@ -29,8 +29,8 @@ import org.slf4j.LoggerFactory;
 
 
 /**
- * Common abstraction class representing services.
+ * Common abstraction class representing services. implementing a general contract @see {@link
- * implementing a general contract @see {@link ChoreographyChapter}
+ * ChoreographyChapter}
  */
 public abstract class Service implements ChoreographyChapter {
   protected static final Logger LOGGER = LoggerFactory.getLogger(Service.class);
@@ -43,9 +43,9 @@ public abstract class Service implements ChoreographyChapter {
 
   @Override
   public Saga execute(Saga saga) {
-    Saga nextSaga = saga;
+    var nextSaga = saga;
     Object nextVal;
-    String chapterName = saga.getCurrent().getName();
+    var chapterName = saga.getCurrent().getName();
     if (chapterName.equals(getName())) {
       if (saga.isForward()) {
         nextSaga = process(saga);
@@ -67,7 +67,7 @@ public abstract class Service implements ChoreographyChapter {
 
       nextSaga.setCurrentValue(nextVal);
     }
-    Saga finalNextSaga = nextSaga;
+    var finalNextSaga = nextSaga;
 
     return sd.find(chapterName).map(ch -> ch.execute(finalNextSaga))
         .orElseThrow(serviceNotFoundException(chapterName));
@@ -80,7 +80,7 @@ public abstract class Service implements ChoreographyChapter {
 
   @Override
   public Saga process(Saga saga) {
-    Object inValue = saga.getCurrentValue();
+    var inValue = saga.getCurrentValue();
     LOGGER.info("The chapter '{}' has been started. "
             + "The data {} has been stored or calculated successfully",
         getName(), inValue);
@@ -91,7 +91,7 @@ public abstract class Service implements ChoreographyChapter {
 
   @Override
   public Saga rollback(Saga saga) {
-    Object inValue = saga.getCurrentValue();
+    var inValue = saga.getCurrentValue();
     LOGGER.info("The Rollback for a chapter '{}' has been started. "
             + "The data {} has been rollbacked successfully",
         getName(), inValue);

saga/src/main/java/com/iluwatar/saga/choreography/WithdrawMoneyService.java

@@ -39,7 +39,7 @@ public class WithdrawMoneyService extends Service {
 
   @Override
   public Saga process(Saga saga) {
-    Object inValue = saga.getCurrentValue();
+    var inValue = saga.getCurrentValue();
 
     if (inValue.equals("bad_order")) {
       LOGGER.info("The chapter '{}' has been started. But the exception has been raised."

saga/src/main/java/com/iluwatar/saga/orchestration/OrchestrationChapter.java

@@ -32,6 +32,7 @@ public interface OrchestrationChapter<K> {
 
   /**
    * method get name.
+   *
    * @return service name.
    */
   String getName();

saga/src/main/java/com/iluwatar/saga/orchestration/Saga.java

@@ -27,9 +27,8 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- * Saga representation.
+ * Saga representation. Saga consists of chapters. Every ChoreographyChapter is executed by a
- * Saga consists of chapters.
+ * certain service.
- * Every ChoreographyChapter is executed by a certain service.
  */
 public class Saga {
 

saga/src/main/java/com/iluwatar/saga/orchestration/SagaApplication.java

@@ -27,23 +27,19 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * This pattern is used in distributed services to perform
+ * This pattern is used in distributed services to perform a group of operations atomically. This is
- * a group of operations atomically.
+ * an analog of transaction in a database but in terms of microservices architecture this is
- * This is an analog of transaction in a database but in terms
+ * executed in a distributed environment
- * of microservices architecture this is executed
- * in a distributed environment
  *
  * <p>A saga is a sequence of local transactions in a certain context.
- * If one transaction fails for some reason,
+ * If one transaction fails for some reason, the saga executes compensating transactions(rollbacks)
- * the saga executes compensating transactions(rollbacks)
  * to undo the impact of the preceding transactions.
  *
  * <p>In this approach, there is an orchestrator @see {@link SagaOrchestrator}
- * that manages all the transactions and directs
+ * that manages all the transactions and directs the participant services to execute local
- * the participant services to execute local transactions based on events.
+ * transactions based on events. The major difference with choreography saga is an ability to handle
- * The major difference with choreography saga is an ability to handle crashed services
+ * crashed services (otherwise in choreography services very hard to prevent a saga if one of them
- * (otherwise in choreography services very hard to prevent a saga
+ * has been crashed)
- * if one of them has been crashed)
  *
  * @see Saga
  * @see SagaOrchestrator
@@ -56,7 +52,7 @@ public class SagaApplication {
    * method to show common saga logic.
    */
   public static void main(String[] args) {
-    SagaOrchestrator sagaOrchestrator = new SagaOrchestrator(newSaga(), serviceDiscovery());
+    var sagaOrchestrator = new SagaOrchestrator(newSaga(), serviceDiscovery());
 
     Saga.Result goodOrder = sagaOrchestrator.execute("good_order");
     Saga.Result badOrder = sagaOrchestrator.execute("bad_order");
@@ -77,8 +73,7 @@ public class SagaApplication {
   }
 
   private static ServiceDiscoveryService serviceDiscovery() {
-    return
+    return new ServiceDiscoveryService()
-        new ServiceDiscoveryService()
         .discover(new OrderService())
         .discover(new FlyBookingService())
         .discover(new HotelBookingService())

saga/src/main/java/com/iluwatar/saga/orchestration/SagaOrchestrator.java

@@ -23,18 +23,18 @@
 
 package com.iluwatar.saga.orchestration;
 
+import static com.iluwatar.saga.orchestration.Saga.Result;
 import static com.iluwatar.saga.orchestration.Saga.Result.CRASHED;
 import static com.iluwatar.saga.orchestration.Saga.Result.FINISHED;
 import static com.iluwatar.saga.orchestration.Saga.Result.ROLLBACK;
 
-import java.util.Optional;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 
 /**
- * The orchestrator that manages all the transactions and directs
+ * The orchestrator that manages all the transactions and directs the participant services to
- * the participant services to execute local transactions based on events.
+ * execute local transactions based on events.
  */
 public class SagaOrchestrator {
   private static final Logger LOGGER = LoggerFactory.getLogger(SagaOrchestrator.class);
@@ -45,6 +45,7 @@ public class SagaOrchestrator {
 
   /**
    * Create a new service to orchetrate sagas.
+   *
    * @param saga saga to process
    * @param sd   service discovery @see {@link ServiceDiscoveryService}
    */
@@ -59,30 +60,30 @@ public class SagaOrchestrator {
    *
    * @param value incoming value
    * @param <K>   type for incoming value
-   * @return result @see {@link Saga.Result}
+   * @return result @see {@link Result}
    */
   @SuppressWarnings("unchecked")
-  public <K> Saga.Result execute(K value) {
+  public <K> Result execute(K value) {
     state.cleanUp();
     LOGGER.info(" The new saga is about to start");
-    Saga.Result result = FINISHED;
+    var result = FINISHED;
     K tempVal = value;
 
     while (true) {
-      int next = state.current();
+      var next = state.current();
-      Saga.Chapter ch = saga.get(next);
+      var ch = saga.get(next);
-      Optional<OrchestrationChapter> srvOpt = sd.find(ch.name);
+      var srvOpt = sd.find(ch.name);
 
-      if (!srvOpt.isPresent()) {
+      if (srvOpt.isEmpty()) {
         state.directionToBack();
         state.back();
         continue;
       }
 
-      OrchestrationChapter srv = srvOpt.get();
+      var srv = srvOpt.get();
 
       if (state.isForward()) {
-        ChapterResult processRes = srv.process(tempVal);
+        var processRes = srv.process(tempVal);
         if (processRes.isSuccess()) {
           next = state.forward();
           tempVal = (K) processRes.getValue();
@@ -90,7 +91,7 @@ public class SagaOrchestrator {
           state.directionToBack();
         }
       } else {
-        ChapterResult rlRes = srv.rollback(tempVal);
+        var rlRes = srv.rollback(tempVal);
         if (rlRes.isSuccess()) {
           next = state.back();
           tempVal = (K) rlRes.getValue();

saga/src/main/java/com/iluwatar/saga/orchestration/Service.java

@@ -27,8 +27,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Common abstraction class representing services.
+ * Common abstraction class representing services. implementing a general contract @see {@link
- * implementing a general contract @see {@link OrchestrationChapter}
+ * OrchestrationChapter}
  *
  * @param <K> type of incoming param
  */

saga/src/test/java/com/iluwatar/saga/choreography/SagaChoreographyTest.java

@@ -33,10 +33,10 @@ public class SagaChoreographyTest {
 
   @Test
   public void executeTest() {
-    ServiceDiscoveryService sd = serviceDiscovery();
+    var sd = serviceDiscovery();
-    ChoreographyChapter service = sd.findAny();
+    var service = sd.findAny();
-    Saga badOrderSaga = service.execute(newSaga("bad_order"));
+    var badOrderSaga = service.execute(newSaga("bad_order"));
-    Saga goodOrderSaga = service.execute(newSaga("good_order"));
+    var goodOrderSaga = service.execute(newSaga("good_order"));
 
     Assert.assertEquals(badOrderSaga.getResult(), Saga.SagaResult.ROLLBACKED);
     Assert.assertEquals(goodOrderSaga.getResult(), Saga.SagaResult.FINISHED);
@@ -52,7 +52,7 @@ public class SagaChoreographyTest {
   }
 
   private static ServiceDiscoveryService serviceDiscovery() {
-    ServiceDiscoveryService sd = new ServiceDiscoveryService();
+    var sd = new ServiceDiscoveryService();
     return sd
         .discover(new OrderService(sd))
         .discover(new FlyBookingService(sd))

saga/src/test/java/com/iluwatar/saga/orchestration/SagaApplicationTest.java

@@ -24,8 +24,6 @@ package com.iluwatar.saga.orchestration;
 
 import org.junit.Test;
 
-import static org.junit.Assert.*;
-
 /**
  * empty test
  */

saga/src/test/java/com/iluwatar/saga/orchestration/SagaOrchestratorInternallyTest.java

@@ -22,11 +22,12 @@
  */
 package com.iluwatar.saga.orchestration;
 
-import org.junit.Assert;
+import static com.iluwatar.saga.orchestration.Saga.Result;
-import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.List;
+import org.junit.Assert;
+import org.junit.Test;
 
 /**
  * test to test orchestration logic
@@ -37,17 +38,16 @@ public class SagaOrchestratorInternallyTest {
 
   @Test
   public void executeTest() {
-    SagaOrchestrator sagaOrchestrator = new SagaOrchestrator(newSaga(), serviceDiscovery());
+    var sagaOrchestrator = new SagaOrchestrator(newSaga(), serviceDiscovery());
-    Saga.Result result = sagaOrchestrator.execute(1);
+    var result = sagaOrchestrator.execute(1);
-    Assert.assertEquals(result, Saga.Result.ROLLBACK);
+    Assert.assertEquals(result, Result.ROLLBACK);
     Assert.assertArrayEquals(
         records.toArray(new String[]{}),
         new String[]{"+1", "+2", "+3", "+4", "-4", "-3", "-2", "-1"});
   }
 
   private static Saga newSaga() {
-    return Saga
+    return Saga.create()
-        .create()
         .chapter("1")
         .chapter("2")
         .chapter("3")
@@ -55,8 +55,7 @@ public class SagaOrchestratorInternallyTest {
   }
 
   private ServiceDiscoveryService serviceDiscovery() {
-    return
+    return new ServiceDiscoveryService()
-        new ServiceDiscoveryService()
         .discover(new Service1())
         .discover(new Service2())
         .discover(new Service3())

semaphore/src/main/java/com/iluwatar/semaphore/App.java

@@ -38,7 +38,7 @@ public class App {
    * main method.
    */
   public static void main(String[] args) {
-    FruitShop shop = new FruitShop();
+    var shop = new FruitShop();
     new Customer("Peter", shop).start();
     new Customer("Paul", shop).start();
     new Customer("Mary", shop).start();

semaphore/src/main/java/com/iluwatar/semaphore/Customer.java

@@ -64,15 +64,16 @@ public class Customer extends Thread {
   public void run() {
 
     while (fruitShop.countFruit() > 0) {
-      FruitBowl bowl = fruitShop.takeBowl();
+      var bowl = fruitShop.takeBowl();
-      Fruit fruit;
+      if (bowl != null) {
-
+        var fruit = bowl.take();
-      if (bowl != null && (fruit = bowl.take()) != null) {
+        if (fruit != null) {
           LOGGER.info("{} took an {}", name, fruit);
           fruitBowl.put(fruit);
           fruitShop.returnBowl(bowl);
         }
       }
+    }
 
     LOGGER.info("{} took {}", name, fruitBowl);
 

semaphore/src/main/java/com/iluwatar/semaphore/FruitBowl.java

@@ -68,11 +68,11 @@ public class FruitBowl {
    * toString method.
    */
   public String toString() {
-    int apples = 0;
+    var apples = 0;
-    int oranges = 0;
+    var oranges = 0;
-    int lemons = 0;
+    var lemons = 0;
 
-    for (Fruit f : fruit) {
+    for (var f : fruit) {
       switch (f.getType()) {
         case APPLE:
           apples++;

semaphore/src/main/java/com/iluwatar/semaphore/FruitShop.java

@@ -55,7 +55,7 @@ public class FruitShop {
    * FruitShop constructor.
    */
   public FruitShop() {
-    for (int i = 0; i < 100; i++) {
+    for (var i = 0; i < 100; i++) {
       bowls[0].put(new Fruit(Fruit.FruitType.APPLE));
       bowls[1].put(new Fruit(Fruit.FruitType.ORANGE));
       bowls[2].put(new Fruit(Fruit.FruitType.LEMON));

semaphore/src/test/java/com/iluwatar/semaphore/AppTest.java

@@ -25,15 +25,12 @@ package com.iluwatar.semaphore;
 
 import org.junit.jupiter.api.Test;
 
-import java.io.IOException;
-
 /**
  * Application Test Entrypoint
  */
 public class AppTest {
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

semaphore/src/test/java/com/iluwatar/semaphore/FruitBowlTest.java

@@ -23,12 +23,12 @@
 
 package com.iluwatar.semaphore;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Test taking from and putting Fruit into a FruitBowl
  */
@@ -36,16 +36,16 @@ public class FruitBowlTest {
 
   @Test
   public void fruitBowlTest() {
-    FruitBowl fbowl = new FruitBowl();
+    var fbowl = new FruitBowl();
 
     assertEquals(0, fbowl.countFruit());
 
-    for (int i = 1; i <= 10; i++) {
+    for (var i = 1; i <= 10; i++) {
       fbowl.put(new Fruit(Fruit.FruitType.LEMON));
       assertEquals(i, fbowl.countFruit());
     }
 
-    for (int i = 9; i >= 0; i--) {
+    for (var i = 9; i >= 0; i--) {
       assertNotNull(fbowl.take());
       assertEquals(i, fbowl.countFruit());
     }

semaphore/src/test/java/com/iluwatar/semaphore/SemaphoreTest.java

@@ -23,11 +23,11 @@
 
 package com.iluwatar.semaphore;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.fail;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Test case for acquiring and releasing a Semaphore
  */
@@ -35,11 +35,11 @@ public class SemaphoreTest {
 
   @Test
   public void acquireReleaseTest() {
-    Semaphore sphore = new Semaphore(3);
+    var sphore = new Semaphore(3);
 
     assertEquals(3, sphore.getAvailableLicenses());
 
-    for (int i = 2; i >= 0; i--) {
+    for (var i = 2; i >= 0; i--) {
       try {
         sphore.acquire();
         assertEquals(i, sphore.getAvailableLicenses());
@@ -48,7 +48,7 @@ public class SemaphoreTest {
       }
     }
 
-    for (int i = 1; i <= 3; i++) {
+    for (var i = 1; i <= 3; i++) {
       sphore.release();
       assertEquals(i, sphore.getAvailableLicenses());
     }

servant/src/main/java/com/iluwatar/servant/App.java

@@ -54,10 +54,10 @@ public class App {
    * Can add a List with enum Actions for variable scenarios.
    */
   public static void scenario(Servant servant, int compliment) {
-    King k = new King();
+    var k = new King();
-    Queen q = new Queen();
+    var q = new Queen();
 
-    List<Royalty> guests = List.of(k, q);
+    var guests = List.of(k, q);
 
     // feed
     servant.feed(k);
@@ -69,9 +69,7 @@ public class App {
     servant.giveCompliments(guests.get(compliment));
 
     // outcome of the night
-    for (Royalty r : guests) {
+    guests.forEach(Royalty::changeMood);
-      r.changeMood();
-    }
 
     // check your luck
     if (servant.checkIfYouWillBeHanged(guests)) {

servant/src/main/java/com/iluwatar/servant/Servant.java

@@ -55,13 +55,6 @@ public class Servant {
    * Check if we will be hanged.
    */
   public boolean checkIfYouWillBeHanged(List<Royalty> tableGuests) {
-    boolean anotherDay = true;
+    return tableGuests.stream().allMatch(Royalty::getMood);
-    for (Royalty r : tableGuests) {
-      if (!r.getMood()) {
-        anotherDay = false;
-      }
-    }
-
-    return anotherDay;
   }
 }

servant/src/test/java/com/iluwatar/servant/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.servant;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

servant/src/test/java/com/iluwatar/servant/KingTest.java

@@ -23,11 +23,11 @@
 
 package com.iluwatar.servant;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 9:40 PM
  *
@@ -37,14 +37,14 @@ public class KingTest {
 
   @Test
   public void testHungrySoberUncomplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.changeMood();
     assertFalse(king.getMood());
   }
 
   @Test
   public void testFedSoberUncomplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.getFed();
     king.changeMood();
     assertFalse(king.getMood());
@@ -52,7 +52,7 @@ public class KingTest {
 
   @Test
   public void testHungryDrunkUncomplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.getDrink();
     king.changeMood();
     assertFalse(king.getMood());
@@ -60,7 +60,7 @@ public class KingTest {
 
   @Test
   public void testHungrySoberComplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.receiveCompliments();
     king.changeMood();
     assertFalse(king.getMood());
@@ -68,7 +68,7 @@ public class KingTest {
 
   @Test
   public void testFedDrunkUncomplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.getFed();
     king.getDrink();
     king.changeMood();
@@ -77,7 +77,7 @@ public class KingTest {
 
   @Test
   public void testFedSoberComplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.getFed();
     king.receiveCompliments();
     king.changeMood();
@@ -86,7 +86,7 @@ public class KingTest {
 
   @Test
   public void testFedDrunkComplimentedKing() {
-    final King king = new King();
+    final var king = new King();
     king.getFed();
     king.getDrink();
     king.receiveCompliments();

servant/src/test/java/com/iluwatar/servant/QueenTest.java

@@ -24,11 +24,11 @@
 package com.iluwatar.servant;
 
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 9:52 PM
  *
@@ -38,7 +38,7 @@ public class QueenTest {
 
   @Test
   public void testNotFlirtyUncomplemented() {
-    final Queen queen = new Queen();
+    final var queen = new Queen();
     queen.setFlirtiness(false);
     queen.changeMood();
     assertFalse(queen.getMood());
@@ -46,7 +46,7 @@ public class QueenTest {
 
   @Test
   public void testNotFlirtyComplemented() {
-    final Queen queen = new Queen();
+    final var queen = new Queen();
     queen.setFlirtiness(false);
     queen.receiveCompliments();
     queen.changeMood();
@@ -55,14 +55,14 @@ public class QueenTest {
 
   @Test
   public void testFlirtyUncomplemented() {
-    final Queen queen = new Queen();
+    final var queen = new Queen();
     queen.changeMood();
     assertFalse(queen.getMood());
   }
 
   @Test
   public void testFlirtyComplemented() {
-    final Queen queen = new Queen();
+    final var queen = new Queen();
     queen.receiveCompliments();
     queen.changeMood();
     assertTrue(queen.getMood());

servant/src/test/java/com/iluwatar/servant/ServantTest.java

@@ -23,16 +23,15 @@
 
 package com.iluwatar.servant;
 
-import org.junit.jupiter.api.Test;
-
-import java.util.List;
-
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.when;
 
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 10:02 PM
  *
@@ -42,8 +41,8 @@ public class ServantTest {
 
   @Test
   public void testFeed() {
-    final Royalty royalty = mock(Royalty.class);
+    final var royalty = mock(Royalty.class);
-    final Servant servant = new Servant("test");
+    final var servant = new Servant("test");
     servant.feed(royalty);
     verify(royalty).getFed();
     verifyNoMoreInteractions(royalty);
@@ -51,8 +50,8 @@ public class ServantTest {
 
   @Test
   public void testGiveWine() {
-    final Royalty royalty = mock(Royalty.class);
+    final var royalty = mock(Royalty.class);
-    final Servant servant = new Servant("test");
+    final var servant = new Servant("test");
     servant.giveWine(royalty);
     verify(royalty).getDrink();
     verifyNoMoreInteractions(royalty);
@@ -60,8 +59,8 @@ public class ServantTest {
 
   @Test
   public void testGiveCompliments() {
-    final Royalty royalty = mock(Royalty.class);
+    final var royalty = mock(Royalty.class);
-    final Servant servant = new Servant("test");
+    final var servant = new Servant("test");
     servant.giveCompliments(royalty);
     verify(royalty).receiveCompliments();
     verifyNoMoreInteractions(royalty);
@@ -69,15 +68,15 @@ public class ServantTest {
 
   @Test
   public void testCheckIfYouWillBeHanged() {
-    final Royalty goodMoodRoyalty = mock(Royalty.class);
+    final var goodMoodRoyalty = mock(Royalty.class);
     when(goodMoodRoyalty.getMood()).thenReturn(true);
 
-    final Royalty badMoodRoyalty = mock(Royalty.class);
+    final var badMoodRoyalty = mock(Royalty.class);
     when(badMoodRoyalty.getMood()).thenReturn(true);
 
-    final List<Royalty> goodCompany = List.of(goodMoodRoyalty, goodMoodRoyalty, goodMoodRoyalty);
+    final var goodCompany = List.of(goodMoodRoyalty, goodMoodRoyalty, goodMoodRoyalty);
 
-    final List<Royalty> badCompany =  List.of(goodMoodRoyalty, goodMoodRoyalty, badMoodRoyalty);
+    final var badCompany = List.of(goodMoodRoyalty, goodMoodRoyalty, badMoodRoyalty);
 
     assertTrue(new Servant("test").checkIfYouWillBeHanged(goodCompany));
     assertTrue(new Servant("test").checkIfYouWillBeHanged(badCompany));

serverless/src/main/java/com/iluwatar/serverless/baas/api/AbstractDynamoDbHandler.java

@@ -24,14 +24,12 @@
 package com.iluwatar.serverless.baas.api;
 
 import com.amazonaws.regions.Regions;
-import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
 import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import java.io.Serializable;
-import java.util.HashMap;
 import java.util.Map;
 
 /**
@@ -50,7 +48,7 @@ public abstract class AbstractDynamoDbHandler<T extends Serializable> {
   }
 
   private void initAmazonDynamoDb() {
-    AmazonDynamoDB amazonDynamoDb = AmazonDynamoDBClientBuilder
+    var amazonDynamoDb = AmazonDynamoDBClientBuilder
         .standard()
         .withRegion(Regions.US_EAST_1)
         .build();
@@ -71,10 +69,7 @@ public abstract class AbstractDynamoDbHandler<T extends Serializable> {
   }
 
   protected Map<String, String> headers() {
-    Map<String, String> headers = new HashMap<>();
+    return Map.of("Content-Type", "application/json");
-    headers.put("Content-Type", "application/json");
-
-    return headers;
   }
 
   /**
@@ -85,14 +80,11 @@ public abstract class AbstractDynamoDbHandler<T extends Serializable> {
    * @return - api gateway proxy response
    */
   protected APIGatewayProxyResponseEvent apiGatewayProxyResponseEvent(Integer statusCode, T body) {
-    APIGatewayProxyResponseEvent apiGatewayProxyResponseEvent =
+    var apiGatewayProxyResponseEvent = new APIGatewayProxyResponseEvent().withHeaders(headers());
-        new APIGatewayProxyResponseEvent().withHeaders(headers());
     try {
       apiGatewayProxyResponseEvent
           .withStatusCode(statusCode)
-          .withBody(getObjectMapper()
+          .withBody(getObjectMapper().writeValueAsString(body));
-              .writeValueAsString(body));
-
     } catch (JsonProcessingException jsonProcessingException) {
       throw new RuntimeException(jsonProcessingException);
     }

serverless/src/main/java/com/iluwatar/serverless/baas/api/FindPersonApiHandler.java

@@ -28,7 +28,6 @@ import com.amazonaws.services.lambda.runtime.RequestHandler;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
 import com.iluwatar.serverless.baas.model.Person;
-import java.util.Map;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -42,15 +41,15 @@ public class FindPersonApiHandler extends AbstractDynamoDbHandler<Person>
   private static final Integer SUCCESS_STATUS_CODE = 200;
 
   @Override
-  public APIGatewayProxyResponseEvent handleRequest(
+  public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent req, Context ctx) {
-      APIGatewayProxyRequestEvent apiGatewayProxyRequestEvent, Context context) {
+    req.getPathParameters().forEach(FindPersonApiHandler::logKeyValue);
-    Map<String, String> pathParameters = apiGatewayProxyRequestEvent.getPathParameters();
+    var id = req.getPathParameters().get("id");
-    pathParameters.keySet().stream().map(key -> key + "=" + pathParameters.get(key))
+    var person = this.getDynamoDbMapper().load(Person.class, id);
-        .forEach(LOG::info);
-
-    Person person = this.getDynamoDbMapper().load(Person.class, apiGatewayProxyRequestEvent
-        .getPathParameters().get("id"));
-
     return apiGatewayProxyResponseEvent(SUCCESS_STATUS_CODE, person);
   }
+
+  private static void logKeyValue(String key, String value) {
+    LOG.info(key + "=" + value);
+  }
+
 }

serverless/src/main/java/com/iluwatar/serverless/baas/api/SavePersonApiHandler.java

@@ -43,19 +43,15 @@ public class SavePersonApiHandler extends AbstractDynamoDbHandler<Person>
   private static final Integer BAD_REQUEST_STATUS_CODE = 400;
 
   @Override
-  public APIGatewayProxyResponseEvent handleRequest(
+  public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent req, Context ctx) {
-      APIGatewayProxyRequestEvent apiGatewayProxyRequestEvent, Context context) {
-    APIGatewayProxyResponseEvent apiGatewayProxyResponseEvent;
-    Person person;
     try {
-      person = getObjectMapper().readValue(apiGatewayProxyRequestEvent.getBody(), Person.class);
+      var objectMapper = getObjectMapper();
+      var person = objectMapper.readValue(req.getBody(), Person.class);
       getDynamoDbMapper().save(person);
-      apiGatewayProxyResponseEvent = apiGatewayProxyResponseEvent(CREATED_STATUS_CODE, person);
+      return apiGatewayProxyResponseEvent(CREATED_STATUS_CODE, person);
     } catch (IOException ioException) {
       LOG.error("unable to parse body", ioException);
-      apiGatewayProxyResponseEvent = apiGatewayProxyResponseEvent(BAD_REQUEST_STATUS_CODE, null);
+      return apiGatewayProxyResponseEvent(BAD_REQUEST_STATUS_CODE, null);
     }
-
-    return apiGatewayProxyResponseEvent;
   }
 }

serverless/src/main/java/com/iluwatar/serverless/baas/model/Address.java

@@ -26,6 +26,7 @@ package com.iluwatar.serverless.baas.model;
 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAttribute;
 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBDocument;
 import java.io.Serializable;
+import java.util.Objects;
 
 /**
  * Address class Created by dheeraj.mummarareddy on 3/4/18.
@@ -96,30 +97,30 @@ public class Address implements Serializable {
       return false;
     }
 
-    Address address = (Address) o;
+    var address = (Address) o;
 
-    if (addressLineOne != null ? !addressLineOne.equals(address.addressLineOne) :
+    if (!Objects.equals(addressLineOne, address.addressLineOne)) {
-        address.addressLineOne != null) {
       return false;
     }
 
-    if (addressLineTwo != null ? !addressLineTwo.equals(address.addressLineTwo) :
+    if (!Objects.equals(addressLineTwo, address.addressLineTwo)) {
-        address.addressLineTwo != null) {
       return false;
     }
 
-    if (city != null ? !city.equals(address.city) : address.city != null) {
+    if (!Objects.equals(city, address.city)) {
       return false;
     }
-    if (state != null ? !state.equals(address.state) : address.state != null) {
+
+    if (!Objects.equals(state, address.state)) {
       return false;
     }
-    return zipCode != null ? zipCode.equals(address.zipCode) : address.zipCode == null;
+
+    return Objects.equals(zipCode, address.zipCode);
   }
 
   @Override
   public int hashCode() {
-    int result = addressLineOne != null ? addressLineOne.hashCode() : 0;
+    var result = addressLineOne != null ? addressLineOne.hashCode() : 0;
     result = 31 * result + (addressLineTwo != null ? addressLineTwo.hashCode() : 0);
     result = 31 * result + (city != null ? city.hashCode() : 0);
     result = 31 * result + (state != null ? state.hashCode() : 0);

serverless/src/main/java/com/iluwatar/serverless/baas/model/Person.java

@@ -29,6 +29,7 @@ import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey;
 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import java.io.Serializable;
+import java.util.Objects;
 
 /**
  * Person class Created by dheeraj.mummarareddy on 3/4/18.
@@ -92,15 +93,15 @@ public class Person implements Serializable {
 
     Person person = (Person) o;
 
-    if (firstName != null ? !firstName.equals(person.firstName) : person.firstName != null) {
+    if (!Objects.equals(firstName, person.firstName)) {
       return false;
     }
 
-    if (lastName != null ? !lastName.equals(person.lastName) : person.lastName != null) {
+    if (!Objects.equals(lastName, person.lastName)) {
       return false;
     }
 
-    return address != null ? address.equals(person.address) : person.address == null;
+    return Objects.equals(address, person.address);
   }
 
   @Override

serverless/src/main/java/com/iluwatar/serverless/faas/ApiGatewayResponse.java

@@ -30,10 +30,8 @@ import java.util.Map;
 
 /**
  * Api gateway response.
- *
- * @param <T> serializable object
  */
-public class ApiGatewayResponse<T extends Serializable> implements Serializable {
+public class ApiGatewayResponse implements Serializable {
 
   private static final long serialVersionUID = 1181159426782844892L;
 
@@ -50,8 +48,12 @@ public class ApiGatewayResponse<T extends Serializable> implements Serializable
    * @param headers         - response headers
    * @param isBase64Encoded - base64Encoded flag
    */
-  public ApiGatewayResponse(Integer statusCode, String body, Map<String, String> headers,
+  public ApiGatewayResponse(
-                            Boolean isBase64Encoded) {
+      Integer statusCode,
+      String body,
+      Map<String, String> headers,
+      Boolean isBase64Encoded
+  ) {
     this.statusCode = statusCode;
     this.body = body;
     this.headers = headers;

serverless/src/main/java/com/iluwatar/serverless/faas/LambdaInfo.java

@@ -24,6 +24,7 @@
 package com.iluwatar.serverless.faas;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 /**
  * Lambda context information.
@@ -110,28 +111,22 @@ public class LambdaInfo implements Serializable {
 
     LambdaInfo that = (LambdaInfo) o;
 
-    if (awsRequestId != null ? !awsRequestId
+    if (!Objects.equals(awsRequestId, that.awsRequestId)) {
-        .equals(that.awsRequestId) : that.awsRequestId != null) {
       return false;
     }
-    if (logGroupName != null ? !logGroupName
+    if (!Objects.equals(logGroupName, that.logGroupName)) {
-        .equals(that.logGroupName) : that.logGroupName != null) {
       return false;
     }
-    if (logStreamName != null ? !logStreamName
+    if (!Objects.equals(logStreamName, that.logStreamName)) {
-        .equals(that.logStreamName) : that.logStreamName != null) {
       return false;
     }
-    if (functionName != null ? !functionName
+    if (!Objects.equals(functionName, that.functionName)) {
-        .equals(that.functionName) : that.functionName != null) {
       return false;
     }
-    if (functionVersion != null ? !functionVersion
+    if (!Objects.equals(functionVersion, that.functionVersion)) {
-        .equals(that.functionVersion) : that.functionVersion != null) {
       return false;
     }
-    return memoryLimitInMb != null ? memoryLimitInMb
+    return Objects.equals(memoryLimitInMb, that.memoryLimitInMb);
-        .equals(that.memoryLimitInMb) : that.memoryLimitInMb == null;
   }
 
   @Override

serverless/src/main/java/com/iluwatar/serverless/faas/api/LambdaInfoApiHandler.java

@@ -27,7 +27,6 @@ import com.amazonaws.services.lambda.runtime.Context;
 import com.amazonaws.services.lambda.runtime.RequestHandler;
 import com.iluwatar.serverless.faas.ApiGatewayResponse;
 import com.iluwatar.serverless.faas.LambdaInfo;
-import java.util.HashMap;
 import java.util.Map;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -46,13 +45,11 @@ public class LambdaInfoApiHandler
   public ApiGatewayResponse handleRequest(Map<String, Object> input, Context context) {
     LOG.info("received: " + input);
 
-    return new ApiGatewayResponse
+    return new ApiGatewayResponse.ApiGatewayResponseBuilder<LambdaInfo>()
-        .ApiGatewayResponseBuilder<LambdaInfo>()
         .headers(headers())
         .statusCode(SUCCESS_STATUS_CODE)
         .body(lambdaInfo(context))
         .build();
-
   }
 
   /**
@@ -69,14 +66,10 @@ public class LambdaInfoApiHandler
     lambdaInfo.setLogGroupName(context.getLogGroupName());
     lambdaInfo.setLogStreamName(context.getLogStreamName());
     lambdaInfo.setMemoryLimitInMb(context.getMemoryLimitInMB());
-
     return lambdaInfo;
   }
 
   private Map<String, String> headers() {
-    var headers = new HashMap<String, String>();
+    return Map.of("Content-Type", "application/json");
-    headers.put("Content-Type", "application/json");
-
-    return headers;
   }
 }

serverless/src/test/java/com/iluwatar/serverless/baas/api/FindPersonApiHandlerTest.java

@@ -23,27 +23,23 @@
 
 package com.iluwatar.serverless.baas.api;
 
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
 import com.amazonaws.services.lambda.runtime.Context;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
-import com.iluwatar.serverless.baas.api.FindPersonApiHandler;
-import com.iluwatar.serverless.baas.api.SavePersonApiHandler;
 import com.iluwatar.serverless.baas.model.Person;
+import java.util.Map;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
-import java.util.Collections;
-
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
-
 /**
- * Unit tests for FindPersonApiHandler
+ * Unit tests for FindPersonApiHandler Created by dheeraj.mummar on 3/5/18.
- * Created by dheeraj.mummar on 3/5/18.
  */
 @RunWith(MockitoJUnitRunner.class)
 public class FindPersonApiHandlerTest {
@@ -66,8 +62,7 @@ public class FindPersonApiHandlerTest {
   }
 
   private APIGatewayProxyRequestEvent apiGatewayProxyRequestEvent() {
-    return new APIGatewayProxyRequestEvent()
+    var request = new APIGatewayProxyRequestEvent();
-        .withPathParamters(Collections
+    return request.withPathParamters(Map.of("id", "37e7a1fe-3544-473d-b764-18128f02d72d"));
-            .singletonMap("id", "37e7a1fe-3544-473d-b764-18128f02d72d"));
   }
 }

serverless/src/test/java/com/iluwatar/serverless/baas/api/SavePersonApiHandlerTest.java

@@ -23,13 +23,15 @@
 
 package com.iluwatar.serverless.baas.api;
 
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
 import com.amazonaws.services.lambda.runtime.Context;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
-import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.iluwatar.serverless.baas.api.SavePersonApiHandler;
 import com.iluwatar.serverless.baas.model.Address;
 import com.iluwatar.serverless.baas.model.Person;
 import org.junit.Assert;
@@ -39,11 +41,8 @@ import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
-import static org.mockito.Mockito.*;
-
 /**
- * Unit tests for SavePersonApiHandler
+ * Unit tests for SavePersonApiHandler Created by dheeraj.mummar on 3/4/18.
- * Created by dheeraj.mummar on 3/4/18.
  */
 @RunWith(MockitoJUnitRunner.class)
 public class SavePersonApiHandlerTest {
@@ -63,40 +62,40 @@ public class SavePersonApiHandlerTest {
 
   @Test
   public void handleRequestSavePersonSuccessful() throws JsonProcessingException {
-    Person person = newPerson();
+    var person = newPerson();
-    APIGatewayProxyResponseEvent apiGatewayProxyResponseEvent =
+    var body = objectMapper.writeValueAsString(person);
-        this.savePersonApiHandler
+    var request = apiGatewayProxyRequestEvent(body);
-            .handleRequest(apiGatewayProxyRequestEvent(objectMapper.writeValueAsString(person)), mock(Context.class));
+    var ctx = mock(Context.class);
+    var apiGatewayProxyResponseEvent = this.savePersonApiHandler.handleRequest(request, ctx);
     verify(dynamoDbMapper, times(1)).save(person);
     Assert.assertNotNull(apiGatewayProxyResponseEvent);
-    Assert.assertEquals(new Integer(201), apiGatewayProxyResponseEvent.getStatusCode());
+    Assert.assertEquals(Integer.valueOf(201), apiGatewayProxyResponseEvent.getStatusCode());
   }
 
   @Test
   public void handleRequestSavePersonException() {
-    APIGatewayProxyResponseEvent apiGatewayProxyResponseEvent =
+    var request = apiGatewayProxyRequestEvent("invalid sample request");
-        this.savePersonApiHandler
+    var ctx = mock(Context.class);
-            .handleRequest(apiGatewayProxyRequestEvent("invalid sample request"), mock(Context.class));
+    var apiGatewayProxyResponseEvent = this.savePersonApiHandler.handleRequest(request, ctx);
     Assert.assertNotNull(apiGatewayProxyResponseEvent);
-    Assert.assertEquals(new Integer(400), apiGatewayProxyResponseEvent.getStatusCode());
+    Assert.assertEquals(Integer.valueOf(400), apiGatewayProxyResponseEvent.getStatusCode());
   }
 
   private APIGatewayProxyRequestEvent apiGatewayProxyRequestEvent(String body) {
-    APIGatewayProxyRequestEvent apiGatewayProxyRequestEvent = new APIGatewayProxyRequestEvent();
+    var apiGatewayProxyRequestEvent = new APIGatewayProxyRequestEvent();
     return apiGatewayProxyRequestEvent.withBody(body);
   }
 
   private Person newPerson() {
-    Person person = new Person();
+    var person = new Person();
     person.setFirstName("Thor");
     person.setLastName("Odinson");
-    Address address = new Address();
+    var address = new Address();
     address.setAddressLineOne("1 Odin ln");
     address.setCity("Asgard");
     address.setState("country of the Gods");
     address.setZipCode("00001");
     person.setAddress(address);
-
     return person;
   }
 }

serverless/src/test/java/com/iluwatar/serverless/faas/api/LambdaInfoApiHandlerTest.java

@@ -23,16 +23,16 @@
 
 package com.iluwatar.serverless.faas.api;
 
-import com.amazonaws.services.lambda.runtime.Context;
-import org.junit.jupiter.api.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
-
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.IsNull.notNullValue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
+import com.amazonaws.services.lambda.runtime.Context;
+import org.junit.jupiter.api.Test;
+import org.junit.runner.RunWith;
+import org.mockito.runners.MockitoJUnitRunner;
+
 /**
  * Unit tests for LambdaInfoApiHandler
  */
@@ -41,8 +41,8 @@ public class LambdaInfoApiHandlerTest {
 
   @Test
   public void handleRequestWithMockContext() {
-    LambdaInfoApiHandler lambdaInfoApiHandler = new LambdaInfoApiHandler();
+    var lambdaInfoApiHandler = new LambdaInfoApiHandler();
-    Context context = mock(Context.class);
+    var context = mock(Context.class);
     when(context.getAwsRequestId()).thenReturn("mock aws request id");
 
     assertThat(lambdaInfoApiHandler.handleRequest(null, context), notNullValue());

service-layer/src/main/java/com/iluwatar/servicelayer/app/App.java

@@ -31,7 +31,6 @@ import com.iluwatar.servicelayer.spellbook.Spellbook;
 import com.iluwatar.servicelayer.spellbook.SpellbookDaoImpl;
 import com.iluwatar.servicelayer.wizard.Wizard;
 import com.iluwatar.servicelayer.wizard.WizardDaoImpl;
-import java.util.List;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -178,29 +177,21 @@ public class App {
    * Query the data.
    */
   public static void queryData() {
-    var service =
+    var wizardDao = new WizardDaoImpl();
-        new MagicServiceImpl(new WizardDaoImpl(), new SpellbookDaoImpl(), new SpellDaoImpl());
+    var spellbookDao = new SpellbookDaoImpl();
+    var spellDao = new SpellDaoImpl();
+    var service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
     LOGGER.info("Enumerating all wizards");
-    for (Wizard w : service.findAllWizards()) {
+    service.findAllWizards().stream().map(Wizard::getName).forEach(LOGGER::info);
-      LOGGER.info(w.getName());
-    }
     LOGGER.info("Enumerating all spellbooks");
-    for (Spellbook s : service.findAllSpellbooks()) {
+    service.findAllSpellbooks().stream().map(Spellbook::getName).forEach(LOGGER::info);
-      LOGGER.info(s.getName());
-    }
     LOGGER.info("Enumerating all spells");
-    for (Spell s : service.findAllSpells()) {
+    service.findAllSpells().stream().map(Spell::getName).forEach(LOGGER::info);
-      LOGGER.info(s.getName());
-    }
     LOGGER.info("Find wizards with spellbook 'Book of Idores'");
-    List<Wizard> wizardsWithSpellbook = service.findWizardsWithSpellbook("Book of Idores");
+    var wizardsWithSpellbook = service.findWizardsWithSpellbook("Book of Idores");
-    for (Wizard w : wizardsWithSpellbook) {
+    wizardsWithSpellbook.forEach(w -> LOGGER.info("{} has 'Book of Idores'", w.getName()));
-      LOGGER.info("{} has 'Book of Idores'", w.getName());
-    }
     LOGGER.info("Find wizards with spell 'Fireball'");
-    List<Wizard> wizardsWithSpell = service.findWizardsWithSpell("Fireball");
+    var wizardsWithSpell = service.findWizardsWithSpell("Fireball");
-    for (Wizard w : wizardsWithSpell) {
+    wizardsWithSpell.forEach(w -> LOGGER.info("{} has 'Fireball'", w.getName()));
-      LOGGER.info("{} has 'Fireball'", w.getName());
-    }
   }
 }

service-layer/src/main/java/com/iluwatar/servicelayer/common/DaoBaseImpl.java

@@ -52,10 +52,9 @@ public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
 
   @Override
   public E find(Long id) {
-    var session = getSessionFactory().openSession();
     Transaction tx = null;
-    E result = null;
+    E result;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       var criteria = session.createCriteria(persistentClass);
       criteria.add(Restrictions.idEq(id));
@@ -66,17 +65,14 @@ public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
     return result;
   }
 
   @Override
   public void persist(E entity) {
-    var session = getSessionFactory().openSession();
     Transaction tx = null;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       session.persist(entity);
       tx.commit();
@@ -85,17 +81,14 @@ public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
   }
 
   @Override
   public E merge(E entity) {
-    var session = getSessionFactory().openSession();
     Transaction tx = null;
     E result = null;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       result = (E) session.merge(entity);
       tx.commit();
@@ -104,17 +97,14 @@ public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
     return result;
   }
 
   @Override
   public void delete(E entity) {
-    var session = getSessionFactory().openSession();
     Transaction tx = null;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       session.delete(entity);
       tx.commit();
@@ -123,17 +113,14 @@ public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
   }
 
   @Override
   public List<E> findAll() {
-    var session = getSessionFactory().openSession();
     Transaction tx = null;
-    List<E> result = null;
+    List<E> result;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       Criteria criteria = session.createCriteria(persistentClass);
       result = criteria.list();
@@ -142,8 +129,6 @@ public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
     return result;
   }

service-layer/src/main/java/com/iluwatar/servicelayer/hibernate/HibernateUtil.java

@@ -54,8 +54,9 @@ public final class HibernateUtil {
   public static synchronized SessionFactory getSessionFactory() {
     if (sessionFactory == null) {
       try {
-        sessionFactory =
+        sessionFactory = new Configuration()
-            new Configuration().addAnnotatedClass(Wizard.class).addAnnotatedClass(Spellbook.class)
+            .addAnnotatedClass(Wizard.class)
+            .addAnnotatedClass(Spellbook.class)
             .addAnnotatedClass(Spell.class)
             .setProperty("hibernate.dialect", "org.hibernate.dialect.H2Dialect")
             .setProperty("hibernate.connection.url", "jdbc:h2:mem:test;DB_CLOSE_DELAY=-1")

service-layer/src/main/java/com/iluwatar/servicelayer/spell/SpellDaoImpl.java

@@ -35,7 +35,7 @@ public class SpellDaoImpl extends DaoBaseImpl<Spell> implements SpellDao {
   @Override
   public Spell findByName(String name) {
     Transaction tx = null;
-    Spell result = null;
+    Spell result;
     try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       var criteria = session.createCriteria(persistentClass);

service-layer/src/main/java/com/iluwatar/servicelayer/spellbook/SpellbookDaoImpl.java

@@ -34,24 +34,19 @@ public class SpellbookDaoImpl extends DaoBaseImpl<Spellbook> implements Spellboo
 
   @Override
   public Spellbook findByName(String name) {
-    var session = getSessionFactory().openSession();
     Transaction tx = null;
-    Spellbook result = null;
+    Spellbook result;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
       var criteria = session.createCriteria(persistentClass);
       criteria.add(Restrictions.eq("name", name));
       result = (Spellbook) criteria.uniqueResult();
-      result.getSpells().size();
-      result.getWizards().size();
       tx.commit();
     } catch (Exception e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
     return result;
   }

service-layer/src/main/java/com/iluwatar/servicelayer/wizard/WizardDaoImpl.java

@@ -24,9 +24,6 @@
 package com.iluwatar.servicelayer.wizard;
 
 import com.iluwatar.servicelayer.common.DaoBaseImpl;
-import com.iluwatar.servicelayer.spellbook.Spellbook;
-import org.hibernate.Criteria;
-import org.hibernate.Session;
 import org.hibernate.Transaction;
 import org.hibernate.criterion.Restrictions;
 
@@ -37,25 +34,19 @@ public class WizardDaoImpl extends DaoBaseImpl<Wizard> implements WizardDao {
 
   @Override
   public Wizard findByName(String name) {
-    Session session = getSessionFactory().openSession();
     Transaction tx = null;
-    Wizard result = null;
+    Wizard result;
-    try {
+    try (var session = getSessionFactory().openSession()) {
       tx = session.beginTransaction();
-      Criteria criteria = session.createCriteria(persistentClass);
+      var criteria = session.createCriteria(persistentClass);
       criteria.add(Restrictions.eq("name", name));
       result = (Wizard) criteria.uniqueResult();
-      for (Spellbook s : result.getSpellbooks()) {
-        s.getSpells().size();
-      }
       tx.commit();
     } catch (Exception e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
-    } finally {
-      session.close();
     }
     return result;
   }

service-layer/src/test/java/com/iluwatar/servicelayer/app/AppTest.java

@@ -28,16 +28,13 @@ import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 
   @AfterEach

service-layer/src/test/java/com/iluwatar/servicelayer/common/BaseDaoTest.java

@@ -23,22 +23,20 @@
 
 package com.iluwatar.servicelayer.common;
 
-import com.iluwatar.servicelayer.hibernate.HibernateUtil;
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
-
-import java.util.List;
-import java.util.concurrent.atomic.AtomicInteger;
-import java.util.function.Function;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
+import com.iluwatar.servicelayer.hibernate.HibernateUtil;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Function;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
 /**
- * Date: 12/28/15 - 10:53 PM
+ * Date: 12/28/15 - 10:53 PM Test for Base Data Access Objects
- * Test for Base Data Access Objects
+ *
  * @param <E> Type of Base Entity
  * @param <D> Type of Dao Base Implementation
  * @author Jeroen Meulemeester
@@ -79,8 +77,8 @@ public abstract class BaseDaoTest<E extends BaseEntity, D extends DaoBaseImpl<E>
   @BeforeEach
   public void setUp() {
     for (int i = 0; i < INITIAL_COUNT; i++) {
-      final String className = dao.persistentClass.getSimpleName();
+      final var className = dao.persistentClass.getSimpleName();
-      final String entityName = String.format("%s%d", className, ID_GENERATOR.incrementAndGet());
+      final var entityName = String.format("%s%d", className, ID_GENERATOR.incrementAndGet());
       this.dao.persist(this.factory.apply(entityName));
     }
   }
@@ -96,9 +94,9 @@ public abstract class BaseDaoTest<E extends BaseEntity, D extends DaoBaseImpl<E>
 
   @Test
   public void testFind() {
-    final List<E> all = this.dao.findAll();
+    final var all = this.dao.findAll();
-    for (final E entity : all) {
+    for (final var entity : all) {
-      final E byId = this.dao.find(entity.getId());
+      final var byId = this.dao.find(entity.getId());
       assertNotNull(byId);
       assertEquals(byId.getId(), byId.getId());
     }
@@ -106,39 +104,39 @@ public abstract class BaseDaoTest<E extends BaseEntity, D extends DaoBaseImpl<E>
 
   @Test
   public void testDelete() {
-    final List<E> originalEntities = this.dao.findAll();
+    final var originalEntities = this.dao.findAll();
     this.dao.delete(originalEntities.get(1));
     this.dao.delete(originalEntities.get(2));
 
-    final List<E> entitiesLeft = this.dao.findAll();
+    final var entitiesLeft = this.dao.findAll();
     assertNotNull(entitiesLeft);
     assertEquals(INITIAL_COUNT - 2, entitiesLeft.size());
   }
 
   @Test
   public void testFindAll() {
-    final List<E> all = this.dao.findAll();
+    final var all = this.dao.findAll();
     assertNotNull(all);
     assertEquals(INITIAL_COUNT, all.size());
   }
 
   @Test
   public void testSetId() {
-    final E entity = this.factory.apply("name");
+    final var entity = this.factory.apply("name");
     assertNull(entity.getId());
 
-    final Long expectedId = 1L;
+    final var expectedId = 1L;
     entity.setId(expectedId);
     assertEquals(expectedId, entity.getId());
   }
 
   @Test
   public void testSetName() {
-    final E entity = this.factory.apply("name");
+    final var entity = this.factory.apply("name");
     assertEquals("name", entity.getName());
     assertEquals("name", entity.toString());
 
-    final String expectedName = "new name";
+    final var expectedName = "new name";
     entity.setName(expectedName);
     assertEquals(expectedName, entity.getName());
     assertEquals(expectedName, entity.toString());

service-layer/src/test/java/com/iluwatar/servicelayer/magic/MagicServiceImplTest.java

@@ -23,18 +23,6 @@
 
 package com.iluwatar.servicelayer.magic;
 
-import com.iluwatar.servicelayer.spell.Spell;
-import com.iluwatar.servicelayer.spell.SpellDao;
-import com.iluwatar.servicelayer.spellbook.Spellbook;
-import com.iluwatar.servicelayer.spellbook.SpellbookDao;
-import com.iluwatar.servicelayer.wizard.Wizard;
-import com.iluwatar.servicelayer.wizard.WizardDao;
-import org.junit.jupiter.api.Test;
-
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.mockito.Matchers.eq;
@@ -44,6 +32,15 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.when;
 
+import com.iluwatar.servicelayer.spell.Spell;
+import com.iluwatar.servicelayer.spell.SpellDao;
+import com.iluwatar.servicelayer.spellbook.Spellbook;
+import com.iluwatar.servicelayer.spellbook.SpellbookDao;
+import com.iluwatar.servicelayer.wizard.Wizard;
+import com.iluwatar.servicelayer.wizard.WizardDao;
+import java.util.Set;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/29/15 - 12:06 AM
  *
@@ -53,11 +50,11 @@ public class MagicServiceImplTest {
 
   @Test
   public void testFindAllWizards() {
-    final WizardDao wizardDao = mock(WizardDao.class);
+    final var wizardDao = mock(WizardDao.class);
-    final SpellbookDao spellbookDao = mock(SpellbookDao.class);
+    final var spellbookDao = mock(SpellbookDao.class);
-    final SpellDao spellDao = mock(SpellDao.class);
+    final var spellDao = mock(SpellDao.class);
 
-    final MagicServiceImpl service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
+    final var service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
     verifyZeroInteractions(wizardDao, spellbookDao, spellDao);
 
     service.findAllWizards();
@@ -66,12 +63,12 @@ public class MagicServiceImplTest {
   }
 
   @Test
-  public void testFindAllSpellbooks() throws Exception {
+  public void testFindAllSpellbooks() {
-    final WizardDao wizardDao = mock(WizardDao.class);
+    final var wizardDao = mock(WizardDao.class);
-    final SpellbookDao spellbookDao = mock(SpellbookDao.class);
+    final var spellbookDao = mock(SpellbookDao.class);
-    final SpellDao spellDao = mock(SpellDao.class);
+    final var spellDao = mock(SpellDao.class);
 
-    final MagicServiceImpl service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
+    final var service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
     verifyZeroInteractions(wizardDao, spellbookDao, spellDao);
 
     service.findAllSpellbooks();
@@ -80,12 +77,12 @@ public class MagicServiceImplTest {
   }
 
   @Test
-  public void testFindAllSpells() throws Exception {
+  public void testFindAllSpells() {
-    final WizardDao wizardDao = mock(WizardDao.class);
+    final var wizardDao = mock(WizardDao.class);
-    final SpellbookDao spellbookDao = mock(SpellbookDao.class);
+    final var spellbookDao = mock(SpellbookDao.class);
-    final SpellDao spellDao = mock(SpellDao.class);
+    final var spellDao = mock(SpellDao.class);
 
-    final MagicServiceImpl service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
+    final var service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
     verifyZeroInteractions(wizardDao, spellbookDao, spellDao);
 
     service.findAllSpells();
@@ -94,26 +91,27 @@ public class MagicServiceImplTest {
   }
 
   @Test
-  public void testFindWizardsWithSpellbook() throws Exception {
+  public void testFindWizardsWithSpellbook() {
-    final String bookname = "bookname";
+    final var bookname = "bookname";
-    final Spellbook spellbook = mock(Spellbook.class);
+    final var spellbook = mock(Spellbook.class);
-    final Set<Wizard> wizards = Set.of(
+    final var wizards = Set.of(
         mock(Wizard.class),
         mock(Wizard.class),
-            mock(Wizard.class));
+        mock(Wizard.class)
+    );
     when(spellbook.getWizards()).thenReturn(wizards);
 
-    final SpellbookDao spellbookDao = mock(SpellbookDao.class);
+    final var spellbookDao = mock(SpellbookDao.class);
     when(spellbookDao.findByName(eq(bookname))).thenReturn(spellbook);
 
-    final WizardDao wizardDao = mock(WizardDao.class);
+    final var wizardDao = mock(WizardDao.class);
-    final SpellDao spellDao = mock(SpellDao.class);
+    final var spellDao = mock(SpellDao.class);
 
 
-    final MagicServiceImpl service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
+    final var service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
     verifyZeroInteractions(wizardDao, spellbookDao, spellDao, spellbook);
 
-    final List<Wizard> result = service.findWizardsWithSpellbook(bookname);
+    final var result = service.findWizardsWithSpellbook(bookname);
     verify(spellbookDao).findByName(eq(bookname));
     verify(spellbook).getWizards();
 
@@ -125,27 +123,28 @@ public class MagicServiceImplTest {
 
   @Test
   public void testFindWizardsWithSpell() throws Exception {
-    final Set<Wizard> wizards = Set.of(
+    final var wizards = Set.of(
         mock(Wizard.class),
         mock(Wizard.class),
-            mock(Wizard.class));
+        mock(Wizard.class)
-    final Spellbook spellbook = mock(Spellbook.class);
+    );
+    final var spellbook = mock(Spellbook.class);
     when(spellbook.getWizards()).thenReturn(wizards);
 
-    final SpellbookDao spellbookDao = mock(SpellbookDao.class);
+    final var spellbookDao = mock(SpellbookDao.class);
-    final WizardDao wizardDao = mock(WizardDao.class);
+    final var wizardDao = mock(WizardDao.class);
 
-    final Spell spell = mock(Spell.class);
+    final var spell = mock(Spell.class);
     when(spell.getSpellbook()).thenReturn(spellbook);
 
-    final String spellName = "spellname";
+    final var spellName = "spellname";
-    final SpellDao spellDao = mock(SpellDao.class);
+    final var spellDao = mock(SpellDao.class);
     when(spellDao.findByName(eq(spellName))).thenReturn(spell);
 
-    final MagicServiceImpl service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
+    final var service = new MagicServiceImpl(wizardDao, spellbookDao, spellDao);
     verifyZeroInteractions(wizardDao, spellbookDao, spellDao, spellbook);
 
-    final List<Wizard> result = service.findWizardsWithSpell(spellName);
+    final var result = service.findWizardsWithSpell(spellName);
     verify(spellDao).findByName(eq(spellName));
     verify(spellbook).getWizards();
 

service-layer/src/test/java/com/iluwatar/servicelayer/spell/SpellDaoImplTest.java

@@ -23,14 +23,12 @@
 
 package com.iluwatar.servicelayer.spell;
 
-import com.iluwatar.servicelayer.common.BaseDaoTest;
-import org.junit.jupiter.api.Test;
-
-import java.util.List;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+import com.iluwatar.servicelayer.common.BaseDaoTest;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 11:02 PM
  *
@@ -44,10 +42,10 @@ public class SpellDaoImplTest extends BaseDaoTest<Spell, SpellDaoImpl> {
 
   @Test
   public void testFindByName() {
-    final SpellDaoImpl dao = getDao();
+    final var dao = getDao();
-    final List<Spell> allSpells = dao.findAll();
+    final var allSpells = dao.findAll();
-    for (final Spell spell : allSpells) {
+    for (final var spell : allSpells) {
-      final Spell spellByName = dao.findByName(spell.getName());
+      final var spellByName = dao.findByName(spell.getName());
       assertNotNull(spellByName);
       assertEquals(spell.getId(), spellByName.getId());
       assertEquals(spell.getName(), spellByName.getName());

service-layer/src/test/java/com/iluwatar/servicelayer/spellbook/SpellbookDaoImplTest.java

@@ -23,14 +23,12 @@
 
 package com.iluwatar.servicelayer.spellbook;
 
-import com.iluwatar.servicelayer.common.BaseDaoTest;
-import org.junit.jupiter.api.Test;
-
-import java.util.List;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+import com.iluwatar.servicelayer.common.BaseDaoTest;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 11:44 PM
  *
@@ -44,10 +42,10 @@ public class SpellbookDaoImplTest extends BaseDaoTest<Spellbook, SpellbookDaoImp
 
   @Test
   public void testFindByName() {
-    final SpellbookDaoImpl dao = getDao();
+    final var dao = getDao();
-    final List<Spellbook> allBooks = dao.findAll();
+    final var allBooks = dao.findAll();
-    for (final Spellbook book : allBooks) {
+    for (final var book : allBooks) {
-      final Spellbook spellByName = dao.findByName(book.getName());
+      final var spellByName = dao.findByName(book.getName());
       assertNotNull(spellByName);
       assertEquals(book.getId(), spellByName.getId());
       assertEquals(book.getName(), spellByName.getName());

service-layer/src/test/java/com/iluwatar/servicelayer/wizard/WizardDaoImplTest.java

@@ -23,14 +23,12 @@
 
 package com.iluwatar.servicelayer.wizard;
 
-import com.iluwatar.servicelayer.common.BaseDaoTest;
-import org.junit.jupiter.api.Test;
-
-import java.util.List;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+import com.iluwatar.servicelayer.common.BaseDaoTest;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/28/15 - 11:46 PM
  *
@@ -44,10 +42,10 @@ public class WizardDaoImplTest extends BaseDaoTest<Wizard, WizardDaoImpl> {
 
   @Test
   public void testFindByName() {
-    final WizardDaoImpl dao = getDao();
+    final var dao = getDao();
-    final List<Wizard> allWizards = dao.findAll();
+    final var allWizards = dao.findAll();
-    for (final Wizard spell : allWizards) {
+    for (final var spell : allWizards) {
-      final Wizard byName = dao.findByName(spell.getName());
+      final var byName = dao.findByName(spell.getName());
       assertNotNull(byName);
       assertEquals(spell.getId(), byName.getId());
       assertEquals(spell.getName(), byName.getName());

service-locator/src/main/java/com/iluwatar/servicelocator/ServiceCache.java

@@ -53,16 +53,15 @@ public class ServiceCache {
    * @return {@link Service}
    */
   public Service getService(String serviceName) {
-    Service cachedService = null;
+    if (serviceCache.containsKey(serviceName)) {
-    for (String serviceJndiName : serviceCache.keySet()) {
+      var cachedService = serviceCache.get(serviceName);
-      if (serviceJndiName.equals(serviceName)) {
+      var name = cachedService.getName();
-        cachedService = serviceCache.get(serviceJndiName);
+      var id = cachedService.getId();
-        LOGGER.info("(cache call) Fetched service {}({}) from cache... !",
+      LOGGER.info("(cache call) Fetched service {}({}) from cache... !", name, id);
-            cachedService.getName(), cachedService.getId());
-      }
-    }
       return cachedService;
     }
+    return null;
+  }
 
   /**
    * Adds the service into the cache map.

service-locator/src/test/java/com/iluwatar/servicelocator/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.servicelocator;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

service-locator/src/test/java/com/iluwatar/servicelocator/ServiceLocatorTest.java

@@ -23,14 +23,15 @@
 
 package com.iluwatar.servicelocator;
 
-import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/29/15 - 19:07 PM
  *
@@ -52,12 +53,10 @@ public class ServiceLocatorTest {
    */
   @Test
   public void testServiceCache() {
-    final String[] serviceNames = new String[]{
+    final var serviceNames = List.of("jndi/serviceA", "jndi/serviceB");
-        "jndi/serviceA", "jndi/serviceB"
-    };
 
-    for (final String serviceName : serviceNames) {
+    for (final var serviceName : serviceNames) {
-      final Service service = ServiceLocator.getService(serviceName);
+      final var service = ServiceLocator.getService(serviceName);
       assertNotNull(service);
       assertEquals(serviceName, service.getName());
       assertTrue(service.getId() > 0); // The id is generated randomly, but the minimum value is '1'

sharding/src/main/java/com/iluwatar/sharding/App.java

@@ -24,14 +24,14 @@
 package com.iluwatar.sharding;
 
 /**
- * Sharding pattern means dividing a data store into a set of horizontal partitions
+ * Sharding pattern means dividing a data store into a set of horizontal partitions or shards. This
- * or shards. This pattern can improve scalability when storing and accessing large
+ * pattern can improve scalability when storing and accessing large volumes of data.
- * volumes of data.
  */
 public class App {
 
   /**
    * Program main entry point.
+   *
    * @param args program runtime arguments
    */
   public static void main(String[] args) {
@@ -45,7 +45,7 @@ public class App {
     var shard2 = new Shard(2);
     var shard3 = new Shard(3);
 
-    ShardManager manager = new LookupShardManager();
+    var manager = new LookupShardManager();
     manager.addNewShard(shard1);
     manager.addNewShard(shard2);
     manager.addNewShard(shard3);
@@ -58,27 +58,27 @@ public class App {
     shard2.clearData();
     shard3.clearData();
 
-    manager = new RangeShardManager();
+    var rangeShardManager = new RangeShardManager();
-    manager.addNewShard(shard1);
+    rangeShardManager.addNewShard(shard1);
-    manager.addNewShard(shard2);
+    rangeShardManager.addNewShard(shard2);
-    manager.addNewShard(shard3);
+    rangeShardManager.addNewShard(shard3);
-    manager.storeData(data1);
+    rangeShardManager.storeData(data1);
-    manager.storeData(data2);
+    rangeShardManager.storeData(data2);
-    manager.storeData(data3);
+    rangeShardManager.storeData(data3);
-    manager.storeData(data4);
+    rangeShardManager.storeData(data4);
 
     shard1.clearData();
     shard2.clearData();
     shard3.clearData();
 
-    manager = new HashShardManager();
+    var hashShardManager = new HashShardManager();
-    manager.addNewShard(shard1);
+    hashShardManager.addNewShard(shard1);
-    manager.addNewShard(shard2);
+    hashShardManager.addNewShard(shard2);
-    manager.addNewShard(shard3);
+    hashShardManager.addNewShard(shard3);
-    manager.storeData(data1);
+    hashShardManager.storeData(data1);
-    manager.storeData(data2);
+    hashShardManager.storeData(data2);
-    manager.storeData(data3);
+    hashShardManager.storeData(data3);
-    manager.storeData(data4);
+    hashShardManager.storeData(data4);
 
     shard1.clearData();
     shard2.clearData();

sharding/src/main/java/com/iluwatar/sharding/LookupShardManager.java

@@ -58,8 +58,7 @@ public class LookupShardManager extends ShardManager {
       return lookupMap.get(key);
     } else {
       var shardCount = shardMap.size();
-      var allocatedShardId = new Random().nextInt(shardCount - 1) + 1;
+      return new Random().nextInt(shardCount - 1) + 1;
-      return allocatedShardId;
     }
   }
 

sharding/src/main/java/com/iluwatar/sharding/RangeShardManager.java

@@ -27,8 +27,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * ShardManager with range strategy. This strategy groups related items together
+ * ShardManager with range strategy. This strategy groups related items together in the same shard,
- * in the same shard, and orders them by shard key.
+ * and orders them by shard key.
  */
 public class RangeShardManager extends ShardManager {
 
@@ -46,21 +46,16 @@ public class RangeShardManager extends ShardManager {
   @Override
   protected int allocateShard(Data data) {
     var type = data.getType();
-    var shardId = -1;
     switch (type) {
       case type1:
-        shardId = 1;
+        return 1;
-        break;
       case type2:
-        shardId = 2;
+        return 2;
-        break;
       case type3:
-        shardId = 3;
+        return 3;
-        break;
       default:
-        break;
+        return -1;
     }
-    return shardId;
   }
 
 }

sharding/src/test/java/com/iluwatar/sharding/AppTest.java

@@ -32,8 +32,7 @@ public class AppTest {
 
   @Test
   public void testMain() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 
 }

sharding/src/test/java/com/iluwatar/sharding/LookupShardManagerTest.java

@@ -24,7 +24,6 @@
 package com.iluwatar.sharding;
 
 import java.util.Map;
-
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
@@ -57,7 +56,7 @@ public class LookupShardManagerTest {
       lookupShardManager.storeData(data);
       var field = LookupShardManager.class.getDeclaredField("lookupMap");
       field.setAccessible(true);
-      Map<Integer, Integer> lookupMap = (Map<Integer, Integer>) field.get(lookupShardManager);
+      var lookupMap = (Map<Integer, Integer>) field.get(lookupShardManager);
       var shardId = lookupMap.get(1);
       var shard = lookupShardManager.getShardById(shardId);
       Assert.assertEquals(data, shard.getDataById(1));

sharding/src/test/java/com/iluwatar/sharding/ShardManagerTest.java

@@ -24,7 +24,6 @@
 package com.iluwatar.sharding;
 
 import java.util.Map;
-
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -57,7 +56,7 @@ public class ShardManagerTest {
       shardManager.addNewShard(shard);
       var field = ShardManager.class.getDeclaredField("shardMap");
       field.setAccessible(true);
-      Map<Integer, Shard> map = (Map<Integer, Shard>) field.get(shardManager);
+      var map = (Map<Integer, Shard>) field.get(shardManager);
       Assert.assertEquals(1, map.size());
       Assert.assertEquals(shard, map.get(1));
     } catch (NoSuchFieldException | IllegalAccessException e) {
@@ -73,7 +72,7 @@ public class ShardManagerTest {
       boolean flag = shardManager.removeShardById(1);
       var field = ShardManager.class.getDeclaredField("shardMap");
       field.setAccessible(true);
-      Map<Integer, Shard> map = (Map<Integer, Shard>) field.get(shardManager);
+      var map = (Map<Integer, Shard>) field.get(shardManager);
       Assert.assertEquals(true, flag);
       Assert.assertEquals(0, map.size());
     } catch (IllegalAccessException | NoSuchFieldException e) {
@@ -83,9 +82,9 @@ public class ShardManagerTest {
 
   @Test
   public void testGetShardById() {
-    Shard shard = new Shard(1);
+    var shard = new Shard(1);
     shardManager.addNewShard(shard);
-    Shard tmpShard = shardManager.getShardById(1);
+    var tmpShard = shardManager.getShardById(1);
     Assert.assertEquals(shard, tmpShard);
   }
 

sharding/src/test/java/com/iluwatar/sharding/ShardTest.java

@@ -25,7 +25,6 @@ package com.iluwatar.sharding;
 
 import java.util.HashMap;
 import java.util.Map;
-
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -48,7 +47,8 @@ public class ShardTest {
   }
 
   @After
-  public void tearDown() {}
+  public void tearDown() {
+  }
 
   @Test
   public void testStoreData() {
@@ -56,7 +56,7 @@ public class ShardTest {
       shard.storeData(data);
       var field = Shard.class.getDeclaredField("dataStore");
       field.setAccessible(true);
-      Map<Integer, Data> dataMap = (Map<Integer, Data>) field.get(shard);
+      var dataMap = (Map<Integer, Data>) field.get(shard);
       Assert.assertEquals(1, dataMap.size());
       Assert.assertEquals(data, dataMap.get(1));
     } catch (NoSuchFieldException | IllegalAccessException e) {
@@ -68,13 +68,13 @@ public class ShardTest {
   @Test
   public void testClearData() {
     try {
-      Map<Integer, Data> dataMap = new HashMap<>();
+      var dataMap = new HashMap<Integer, Data>();
       dataMap.put(1, data);
       var field = Shard.class.getDeclaredField("dataStore");
       field.setAccessible(true);
       field.set(shard, dataMap);
       shard.clearData();
-      dataMap = (Map<Integer, Data>) field.get(shard);
+      dataMap = (HashMap<Integer, Data>) field.get(shard);
       Assert.assertEquals(0, dataMap.size());
     } catch (NoSuchFieldException | IllegalAccessException e) {
       Assert.fail("Fail to modify field access.");

singleton/README.md

@@ -41,8 +41,8 @@ public enum EnumIvoryTower {
 Then in order to use
 
 ```java
-EnumIvoryTower enumIvoryTower1 = EnumIvoryTower.INSTANCE;
+var enumIvoryTower1 = EnumIvoryTower.INSTANCE;
-EnumIvoryTower enumIvoryTower2 = EnumIvoryTower.INSTANCE;
+var enumIvoryTower2 = EnumIvoryTower.INSTANCE;
 assertEquals(enumIvoryTower1, enumIvoryTower2); // true
 ```
 

singleton/src/main/java/com/iluwatar/singleton/App.java

@@ -45,8 +45,7 @@ import org.slf4j.LoggerFactory;
  * example is found in {@link EnumIvoryTower}. At first glance the code looks short and simple.
  * However, you should be aware of the downsides including committing to implementation strategy,
  * extending the enum class, serializability and restrictions to coding. These are extensively
- * discussed in Stack Overflow:
+ * discussed in Stack Overflow: http://programmers.stackexchange.com/questions/179386/what-are-the-downsides-of-implementing
- * http://programmers.stackexchange.com/questions/179386/what-are-the-downsides-of-implementing
  * -a-singleton-with-javas-enum</p>
  *
  * <p>{@link ThreadSafeLazyLoadedIvoryTower} is a Singleton implementation that is initialized on
@@ -54,9 +53,9 @@ import org.slf4j.LoggerFactory;
  * synchronized.</p>
  *
  * <p>Another Singleton implementation that is initialized on demand is found in
- * {@link ThreadSafeDoubleCheckLocking}. It is somewhat faster than
+ * {@link ThreadSafeDoubleCheckLocking}. It is somewhat faster than {@link
- * {@link ThreadSafeLazyLoadedIvoryTower} since it doesn't synchronize the whole access method but
+ * ThreadSafeLazyLoadedIvoryTower} since it doesn't synchronize the whole access method but only the
- * only the method internals on specific conditions.</p>
+ * method internals on specific conditions.</p>
  *
  * <p>Yet another way to implement thread safe lazily initialized Singleton can be found in
  * {@link InitializingOnDemandHolderIdiom}. However, this implementation requires at least Java 8
@@ -80,10 +79,8 @@ public class App {
     LOGGER.info("ivoryTower2={}", ivoryTower2);
 
     // lazily initialized singleton
-    var threadSafeIvoryTower1 =
+    var threadSafeIvoryTower1 = ThreadSafeLazyLoadedIvoryTower.getInstance();
-        ThreadSafeLazyLoadedIvoryTower.getInstance();
+    var threadSafeIvoryTower2 = ThreadSafeLazyLoadedIvoryTower.getInstance();
-    var threadSafeIvoryTower2 =
-        ThreadSafeLazyLoadedIvoryTower.getInstance();
     LOGGER.info("threadSafeIvoryTower1={}", threadSafeIvoryTower1);
     LOGGER.info("threadSafeIvoryTower2={}", threadSafeIvoryTower2);
 
@@ -100,11 +97,9 @@ public class App {
     LOGGER.info(dcl2.toString());
 
     // initialize on demand holder idiom
-    var demandHolderIdiom =
+    var demandHolderIdiom = InitializingOnDemandHolderIdiom.getInstance();
-        InitializingOnDemandHolderIdiom.getInstance();
     LOGGER.info(demandHolderIdiom.toString());
-    var demandHolderIdiom2 =
+    var demandHolderIdiom2 = InitializingOnDemandHolderIdiom.getInstance();
-        InitializingOnDemandHolderIdiom.getInstance();
     LOGGER.info(demandHolderIdiom2.toString());
   }
 }

singleton/src/test/java/com/iluwatar/singleton/AppTest.java

@@ -32,7 +32,6 @@ public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

singleton/src/test/java/com/iluwatar/singleton/SingletonTest.java

@@ -29,13 +29,11 @@ import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTimeout;
 
 import java.util.ArrayList;
-import java.util.List;
 import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.concurrent.Future;
 import java.util.function.Supplier;
-
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import org.junit.jupiter.api.Test;
 
 /**
@@ -73,9 +71,9 @@ public abstract class SingletonTest<S> {
   @Test
   public void testMultipleCallsReturnTheSameObjectInSameThread() {
     // Create several instances in the same calling thread
-    S instance1 = this.singletonInstanceMethod.get();
+    var instance1 = this.singletonInstanceMethod.get();
-    S instance2 = this.singletonInstanceMethod.get();
+    var instance2 = this.singletonInstanceMethod.get();
-    S instance3 = this.singletonInstanceMethod.get();
+    var instance3 = this.singletonInstanceMethod.get();
     // now check they are equal
     assertSame(instance1, instance2);
     assertSame(instance1, instance3);
@@ -89,19 +87,18 @@ public abstract class SingletonTest<S> {
   public void testMultipleCallsReturnTheSameObjectInDifferentThreads() throws Exception {
     assertTimeout(ofMillis(10000), () -> {
       // Create 10000 tasks and inside each callable instantiate the singleton class
-      final List<Callable<S>> tasks = new ArrayList<>();
+      final var tasks = IntStream.range(0, 10000)
-      for (int i = 0; i < 10000; i++) {
+          .<Callable<S>>mapToObj(i -> this.singletonInstanceMethod::get)
-        tasks.add(this.singletonInstanceMethod::get);
+          .collect(Collectors.toCollection(ArrayList::new));
-      }
 
       // Use up to 8 concurrent threads to handle the tasks
-      final ExecutorService executorService = Executors.newFixedThreadPool(8);
+      final var executorService = Executors.newFixedThreadPool(8);
-      final List<Future<S>> results = executorService.invokeAll(tasks);
+      final var results = executorService.invokeAll(tasks);
 
       // wait for all of the threads to complete
-      final S expectedInstance = this.singletonInstanceMethod.get();
+      final var expectedInstance = this.singletonInstanceMethod.get();
-      for (Future<S> res : results) {
+      for (var res : results) {
-        final S instance = res.get();
+        final var instance = res.get();
         assertNotNull(instance);
         assertSame(expectedInstance, instance);
       }

singleton/src/test/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLockingTest.java

@@ -23,9 +23,7 @@
 
 package com.iluwatar.singleton;
 
-import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
-
 import org.junit.Test;
 
 /**
@@ -47,11 +45,10 @@ public class ThreadSafeDoubleCheckLockingTest extends SingletonTest<ThreadSafeDo
    */
   @Test(expected = InvocationTargetException.class)
   public void testCreatingNewInstanceByRefection() throws Exception {
-    ThreadSafeDoubleCheckLocking instance1 = ThreadSafeDoubleCheckLocking.getInstance();
+    ThreadSafeDoubleCheckLocking.getInstance();
-    Constructor constructor = ThreadSafeDoubleCheckLocking.class.getDeclaredConstructor();
+    var constructor = ThreadSafeDoubleCheckLocking.class.getDeclaredConstructor();
     constructor.setAccessible(true);
-    ThreadSafeDoubleCheckLocking instance2 =
+    constructor.newInstance((Object[]) null);
-            (ThreadSafeDoubleCheckLocking) constructor.newInstance(null);
   }
 
 }

spatial-partition/README.md

@@ -19,9 +19,9 @@ Say, you are building a war game with hundreds, or maybe even thousands of playe
 
 ```java
 public void handleMeLee(Unit units[], int numUnits) {
-  for (int a = 0; a < numUnits - 1; a++)
+  for (var a = 0; a < numUnits - 1; a++)
   {
-    for (int b = a + 1; b < numUnits; b++)
+    for (var b = a + 1; b < numUnits; b++)
     {
       if (units[a].position() == units[b].position())
       {

spatial-partition/src/main/java/com/iluwatar/spatialpartition/App.java

@@ -23,8 +23,6 @@
 
 package com.iluwatar.spatialpartition;
 
-import java.util.ArrayList;
-import java.util.Enumeration;
 import java.util.Hashtable;
 import java.util.Random;
 import org.slf4j.Logger;
@@ -62,58 +60,46 @@ import org.slf4j.LoggerFactory;
 public class App {
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
 
-  static void noSpatialPartition(int height, int width,
+  static void noSpatialPartition(int numOfMovements, Hashtable<Integer, Bubble> bubbles) {
-                                 int numOfMovements, Hashtable<Integer, Bubble> bubbles) {
+    //all bubbles have to be checked for collision for all bubbles
-    ArrayList<Point> bubblesToCheck = new ArrayList<Point>();
+    var bubblesToCheck = bubbles.values();
-    for (Enumeration<Integer> e = bubbles.keys(); e.hasMoreElements(); ) {
-      bubblesToCheck.add(bubbles
-          .get(e.nextElement())); //all bubbles have to be checked for collision for all bubbles
-    }
 
     //will run numOfMovement times or till all bubbles have popped
     while (numOfMovements > 0 && !bubbles.isEmpty()) {
-      for (Enumeration<Integer> e = bubbles.keys(); e.hasMoreElements(); ) {
+      bubbles.forEach((i, bubble) -> {
-        Integer i = e.nextElement();
         // bubble moves, new position gets updated
         // and collisions are checked with all bubbles in bubblesToCheck
-        bubbles.get(i).move();
+        bubble.move();
-        bubbles.replace(i, bubbles.get(i));
+        bubbles.replace(i, bubble);
-        bubbles.get(i).handleCollision(bubblesToCheck, bubbles);
+        bubble.handleCollision(bubblesToCheck, bubbles);
-      }
+      });
       numOfMovements--;
     }
-    for (Integer key : bubbles.keySet()) {
     //bubbles not popped
-      LOGGER.info("Bubble " + key + " not popped");
+    bubbles.keySet().stream().map(key -> "Bubble " + key + " not popped").forEach(LOGGER::info);
-    }
   }
 
   static void withSpatialPartition(
       int height, int width, int numOfMovements, Hashtable<Integer, Bubble> bubbles) {
     //creating quadtree
-    Rect rect = new Rect(width / 2, height / 2, width, height);
+    var rect = new Rect(width / 2, height / 2, width, height);
-    QuadTree quadTree = new QuadTree(rect, 4);
+    var quadTree = new QuadTree(rect, 4);
 
     //will run numOfMovement times or till all bubbles have popped
     while (numOfMovements > 0 && !bubbles.isEmpty()) {
       //quadtree updated each time
-      for (Enumeration<Integer> e = bubbles.keys(); e.hasMoreElements(); ) {
+      bubbles.values().forEach(quadTree::insert);
-        quadTree.insert(bubbles.get(e.nextElement()));
+      bubbles.forEach((i, bubble) -> {
-      }
-      for (Enumeration<Integer> e = bubbles.keys(); e.hasMoreElements(); ) {
-        Integer i = e.nextElement();
         //bubble moves, new position gets updated, quadtree used to reduce computations
-        bubbles.get(i).move();
+        bubble.move();
-        bubbles.replace(i, bubbles.get(i));
+        bubbles.replace(i, bubble);
-        SpatialPartitionBubbles sp = new SpatialPartitionBubbles(bubbles, quadTree);
+        var sp = new SpatialPartitionBubbles(bubbles, quadTree);
-        sp.handleCollisionsUsingQt(bubbles.get(i));
+        sp.handleCollisionsUsingQt(bubble);
-      }
+      });
       numOfMovements--;
     }
-    for (Integer key : bubbles.keySet()) {
     //bubbles not popped
-      LOGGER.info("Bubble " + key + " not popped");
+    bubbles.keySet().stream().map(key -> "Bubble " + key + " not popped").forEach(LOGGER::info);
-    }
   }
 
   /**
@@ -123,23 +109,23 @@ public class App {
    */
 
   public static void main(String[] args) {
-    Hashtable<Integer, Bubble> bubbles1 = new Hashtable<Integer, Bubble>();
+    var bubbles1 = new Hashtable<Integer, Bubble>();
-    Hashtable<Integer, Bubble> bubbles2 = new Hashtable<Integer, Bubble>();
+    var bubbles2 = new Hashtable<Integer, Bubble>();
-    Random rand = new Random();
+    var rand = new Random();
     for (int i = 0; i < 10000; i++) {
-      Bubble b = new Bubble(rand.nextInt(300), rand.nextInt(300), i, rand.nextInt(2) + 1);
+      var b = new Bubble(rand.nextInt(300), rand.nextInt(300), i, rand.nextInt(2) + 1);
       bubbles1.put(i, b);
       bubbles2.put(i, b);
       LOGGER.info("Bubble " + i + " with radius " + b.radius
           + " added at (" + b.coordinateX + "," + b.coordinateY + ")");
     }
 
-    long start1 = System.currentTimeMillis();
+    var start1 = System.currentTimeMillis();
-    App.noSpatialPartition(300, 300, 20, bubbles1);
+    App.noSpatialPartition(20, bubbles1);
-    long end1 = System.currentTimeMillis();
+    var end1 = System.currentTimeMillis();
-    long start2 = System.currentTimeMillis();
+    var start2 = System.currentTimeMillis();
     App.withSpatialPartition(300, 300, 20, bubbles2);
-    long end2 = System.currentTimeMillis();
+    var end2 = System.currentTimeMillis();
     LOGGER.info("Without spatial partition takes " + (end1 - start1) + "ms");
     LOGGER.info("With spatial partition takes " + (end2 - start2) + "ms");
   }

spatial-partition/src/main/java/com/iluwatar/spatialpartition/Bubble.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.spatialpartition;
 
-import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Hashtable;
 import java.util.Random;
 import org.slf4j.Logger;
@@ -64,10 +64,10 @@ public class Bubble extends Point<Bubble> {
     allBubbles.remove(this.id);
   }
 
-  void handleCollision(ArrayList<Point> bubblesToCheck, Hashtable<Integer, Bubble> allBubbles) {
+  void handleCollision(Collection<? extends Point> toCheck, Hashtable<Integer, Bubble> allBubbles) {
-    boolean toBePopped = false; //if any other bubble collides with it, made true
+    var toBePopped = false; //if any other bubble collides with it, made true
-    for (int i = 0; i < bubblesToCheck.size(); i++) {
+    for (var point : toCheck) {
-      Integer otherId = bubblesToCheck.get(i).id;
+      var otherId = point.id;
       if (allBubbles.get(otherId) != null && //the bubble hasn't been popped yet
           this.id != otherId && //the two bubbles are not the same
           this.touches(allBubbles.get(otherId))) { //the bubbles touch

spatial-partition/src/main/java/com/iluwatar/spatialpartition/Point.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.spatialpartition;
 
-import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Hashtable;
 
 /**
@@ -61,8 +61,8 @@ public abstract class Point<T> {
   /**
    * handling interactions/collisions with other objects.
    *
-   * @param pointsToCheck contains the objects which need to be checked
+   * @param toCheck contains the objects which need to be checked
-   * @param allPoints     contains hashtable of all points on field at this time
+   * @param all     contains hashtable of all points on field at this time
    */
-  abstract void handleCollision(ArrayList<Point> pointsToCheck, Hashtable<Integer, T> allPoints);
+  abstract void handleCollision(Collection<? extends Point> toCheck, Hashtable<Integer, T> all);
 }

spatial-partition/src/main/java/com/iluwatar/spatialpartition/QuadTree.java

@@ -23,8 +23,7 @@
 
 package com.iluwatar.spatialpartition;
 
-import java.util.ArrayList;
+import java.util.Collection;
-import java.util.Enumeration;
 import java.util.Hashtable;
 
 /**
@@ -47,7 +46,7 @@ public class QuadTree {
     this.boundary = boundary;
     this.capacity = capacity;
     this.divided = false;
-    this.points = new Hashtable<Integer, Point>();
+    this.points = new Hashtable<>();
     this.northwest = null;
     this.northeast = null;
     this.southwest = null;
@@ -76,30 +75,29 @@ public class QuadTree {
   }
 
   void divide() {
-    double x = this.boundary.coordinateX;
+    var x = this.boundary.coordinateX;
-    double y = this.boundary.coordinateY;
+    var y = this.boundary.coordinateY;
-    double width = this.boundary.width;
+    var width = this.boundary.width;
-    double height = this.boundary.height;
+    var height = this.boundary.height;
-    Rect nw = new Rect(x - width / 4, y + height / 4, width / 2, height / 2);
+    var nw = new Rect(x - width / 4, y + height / 4, width / 2, height / 2);
     this.northwest = new QuadTree(nw, this.capacity);
-    Rect ne = new Rect(x + width / 4, y + height / 4, width / 2, height / 2);
+    var ne = new Rect(x + width / 4, y + height / 4, width / 2, height / 2);
     this.northeast = new QuadTree(ne, this.capacity);
-    Rect sw = new Rect(x - width / 4, y - height / 4, width / 2, height / 2);
+    var sw = new Rect(x - width / 4, y - height / 4, width / 2, height / 2);
     this.southwest = new QuadTree(sw, this.capacity);
-    Rect se = new Rect(x + width / 4, y - height / 4, width / 2, height / 2);
+    var se = new Rect(x + width / 4, y - height / 4, width / 2, height / 2);
     this.southeast = new QuadTree(se, this.capacity);
     this.divided = true;
   }
 
-  ArrayList<Point> query(Rect r, ArrayList<Point> relevantPoints) {
+  Collection<Point> query(Rect r, Collection<Point> relevantPoints) {
     //could also be a circle instead of a rectangle
     if (this.boundary.intersects(r)) {
-      for (Enumeration<Integer> e = this.points.keys(); e.hasMoreElements(); ) {
+      this.points
-        Integer i = e.nextElement();
+          .values()
-        if (r.contains(this.points.get(i))) {
+          .stream()
-          relevantPoints.add(this.points.get(i));
+          .filter(r::contains)
-        }
+          .forEach(relevantPoints::add);
-      }
       if (this.divided) {
         this.northwest.query(r, relevantPoints);
         this.northeast.query(r, relevantPoints);

spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionBubbles.java

@@ -24,6 +24,7 @@
 package com.iluwatar.spatialpartition;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Hashtable;
 
 /**
@@ -44,8 +45,8 @@ public class SpatialPartitionBubbles extends SpatialPartitionGeneric<Bubble> {
   void handleCollisionsUsingQt(Bubble b) {
     // finding points within area of a square drawn with centre same as
     // centre of bubble and length = radius of bubble
-    Rect rect = new Rect(b.coordinateX, b.coordinateY, 2 * b.radius, 2 * b.radius);
+    var rect = new Rect(b.coordinateX, b.coordinateY, 2 * b.radius, 2 * b.radius);
-    ArrayList<Point> quadTreeQueryResult = new ArrayList<Point>();
+    var quadTreeQueryResult = new ArrayList<Point>();
     this.quadTree.query(rect, quadTreeQueryResult);
     //handling these collisions
     b.handleCollision(quadTreeQueryResult, this.bubbles);

spatial-partition/src/test/java/com/iluwatar/spatialpartition/BubbleTest.java

@@ -23,62 +23,71 @@
 
 package com.iluwatar.spatialpartition;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import java.util.ArrayList;
 import java.util.Hashtable;
 import org.junit.jupiter.api.Test;
 
 /**
-* Testing methods in Bubble class.
+ * Testing methods in Bubble class.
-*/
+ */
 
 class BubbleTest {
 
   @Test
   void moveTest() {
-    Bubble b = new Bubble(10,10,1,2);
+    var b = new Bubble(10, 10, 1, 2);
-    int initialX = b.coordinateX;
+    var initialX = b.coordinateX;
-    int initialY = b.coordinateY;
+    var initialY = b.coordinateY;
     b.move();
     //change in x and y < |2|
-    assertTrue((b.coordinateX - initialX < 2 && b.coordinateX - initialX > -2) && (b.coordinateY - initialY < 2 && b.coordinateY - initialY > -2));
+    assertTrue(b.coordinateX - initialX < 2 && b.coordinateX - initialX > -2);
+    assertTrue(b.coordinateY - initialY < 2 && b.coordinateY - initialY > -2);
   }
 
   @Test
   void touchesTest() {
-    Bubble b1 = new Bubble(0,0,1,2);
+    var b1 = new Bubble(0, 0, 1, 2);
-    Bubble b2 = new Bubble(1,1,2,1);
+    var b2 = new Bubble(1, 1, 2, 1);
-    Bubble b3 = new Bubble(10,10,3,1);
+    var b3 = new Bubble(10, 10, 3, 1);
     //b1 touches b2 but not b3
-    assertTrue(b1.touches(b2) && !b1.touches(b3));
+    assertTrue(b1.touches(b2));
+    assertFalse(b1.touches(b3));
   }
 
   @Test
   void popTest() {
-    Bubble b1 = new Bubble(10,10,1,2);
+    var b1 = new Bubble(10, 10, 1, 2);
-    Bubble b2 = new Bubble(0,0,2,2);
+    var b2 = new Bubble(0, 0, 2, 2);
-    Hashtable<Integer, Bubble> bubbles = new Hashtable<Integer, Bubble>();
+    var bubbles = new Hashtable<Integer, Bubble>();
     bubbles.put(1, b1);
     bubbles.put(2, b2);
     b1.pop(bubbles);
     //after popping, bubble no longer in hashtable containing all bubbles
-    assertTrue(bubbles.get(1) == null && bubbles.get(2) != null);
+    assertNull(bubbles.get(1));
+    assertNotNull(bubbles.get(2));
   }
 
   @Test
   void handleCollisionTest() {
-    Bubble b1 = new Bubble(0,0,1,2);
+    var b1 = new Bubble(0, 0, 1, 2);
-    Bubble b2 = new Bubble(1,1,2,1);
+    var b2 = new Bubble(1, 1, 2, 1);
-    Bubble b3 = new Bubble(10,10,3,1);
+    var b3 = new Bubble(10, 10, 3, 1);
-    Hashtable<Integer, Bubble> bubbles = new Hashtable<Integer, Bubble>();
+    var bubbles = new Hashtable<Integer, Bubble>();
     bubbles.put(1, b1);
     bubbles.put(2, b2);
     bubbles.put(3, b3);
-    ArrayList<Point> bubblesToCheck = new ArrayList<Point>();
+    var bubblesToCheck = new ArrayList<Point>();
     bubblesToCheck.add(b2);
     bubblesToCheck.add(b3);
     b1.handleCollision(bubblesToCheck, bubbles);
     //b1 touches b2 and not b3, so b1, b2 will be popped
-    assertTrue(bubbles.get(1) == null && bubbles.get(2) == null && bubbles.get(3) != null);
+    assertNull(bubbles.get(1));
+    assertNull(bubbles.get(2));
+    assertNotNull(bubbles.get(3));
   }
 }

spatial-partition/src/test/java/com/iluwatar/spatialpartition/QuadTreeTest.java

@@ -23,12 +23,13 @@
 
 package com.iluwatar.spatialpartition;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Hashtable;
 import java.util.Random;
-
+import java.util.stream.Collectors;
-
 import org.junit.jupiter.api.Test;
 
 /**
@@ -39,41 +40,34 @@ class QuadTreeTest {
 
   @Test
   void queryTest() {
-    ArrayList<Point> points = new ArrayList<Point>();
+    var points = new ArrayList<Point>();
-    Random rand = new Random();
+    var rand = new Random();
     for (int i = 0; i < 20; i++) {
-      Bubble p = new Bubble(rand.nextInt(300), rand.nextInt(300), i, rand.nextInt(2) + 1);
+      var p = new Bubble(rand.nextInt(300), rand.nextInt(300), i, rand.nextInt(2) + 1);
       points.add(p);
     }
-    Rect field = new Rect(150,150,300,300); //size of field
+    var field = new Rect(150, 150, 300, 300); //size of field
-    Rect queryRange = new Rect(70,130,100,100); //result = all points lying in this rectangle
+    var queryRange = new Rect(70, 130, 100, 100); //result = all points lying in this rectangle
     //points found in the query range using quadtree and normal method is same
-    assertTrue(QuadTreeTest.quadTreeTest(points, field, queryRange).equals(QuadTreeTest.verify(points, queryRange)));
+    var points1 = QuadTreeTest.quadTreeTest(points, field, queryRange);
+    var points2 = QuadTreeTest.verify(points, queryRange);
+    assertEquals(points1, points2);
   }
 
-  static Hashtable<Integer, Point> quadTreeTest(ArrayList<Point> points, Rect field, Rect queryRange) {
+  static Hashtable<Integer, Point> quadTreeTest(Collection<Point> points, Rect field, Rect queryRange) {
     //creating quadtree and inserting all points
-    QuadTree qTree = new QuadTree(queryRange, 4);
+    var qTree = new QuadTree(queryRange, 4);
-    for (int i = 0; i < points.size(); i++) {
+    points.forEach(qTree::insert);
-      qTree.insert(points.get(i));
+
+    return qTree
+        .query(field, new ArrayList<>())
+        .stream()
+        .collect(Collectors.toMap(p -> p.id, p -> p, (a, b) -> b, Hashtable::new));
   }
 
-    ArrayList<Point> queryResult = qTree.query(field, new ArrayList<Point>());
+  static Hashtable<Integer, Point> verify(Collection<Point> points, Rect queryRange) {
-    Hashtable<Integer, Point> result = new Hashtable<Integer, Point>();
+    return points.stream()
-    for (int i = 0; i < queryResult.size(); i++) {
+        .filter(queryRange::contains)
-      Point p = queryResult.get(i);
+        .collect(Collectors.toMap(point -> point.id, point -> point, (a, b) -> b, Hashtable::new));
-      result.put(p.id, p);
-    }
-    return result;
-  }
-
-  static Hashtable<Integer, Point> verify(ArrayList<Point> points, Rect queryRange) {
-    Hashtable<Integer, Point> result = new Hashtable<Integer, Point>();
-    for (int i = 0; i < points.size(); i++) {
-      if (queryRange.contains(points.get(i))) {
-        result.put(points.get(i).id, points.get(i));
-      }
-    }
-    return result;
   }
 }

spatial-partition/src/test/java/com/iluwatar/spatialpartition/RectTest.java

@@ -23,7 +23,9 @@
 
 package com.iluwatar.spatialpartition;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import org.junit.jupiter.api.Test;
 
 /**
@@ -34,19 +36,21 @@ class RectTest {
 
   @Test
   void containsTest() {
-    Rect r = new Rect(10,10,20,20);
+    var r = new Rect(10, 10, 20, 20);
-    Bubble b1 = new Bubble(2,2,1,1);
+    var b1 = new Bubble(2, 2, 1, 1);
-    Bubble b2 = new Bubble(30,30,2,1);
+    var b2 = new Bubble(30, 30, 2, 1);
     //r contains b1 and not b2
-    assertTrue(r.contains(b1) && !r.contains(b2));
+    assertTrue(r.contains(b1));
+    assertFalse(r.contains(b2));
   }
 
   @Test
   void intersectsTest() {
-    Rect r1 = new Rect(10,10,20,20);
+    var r1 = new Rect(10, 10, 20, 20);
-    Rect r2 = new Rect(15,15,20,20);
+    var r2 = new Rect(15, 15, 20, 20);
-    Rect r3 = new Rect(50,50,20,20);
+    var r3 = new Rect(50, 50, 20, 20);
     //r1 intersects r2 and not r3
-    assertTrue(r1.intersects(r2) && !r1.intersects(r3));
+    assertTrue(r1.intersects(r2));
+    assertFalse(r1.intersects(r3));
   }
 }

spatial-partition/src/test/java/com/iluwatar/spatialpartition/SpatialPartitionBubblesTest.java

@@ -23,7 +23,9 @@
 
 package com.iluwatar.spatialpartition;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
 import java.util.Hashtable;
 import org.junit.jupiter.api.Test;
 
@@ -35,24 +37,27 @@ class SpatialPartitionBubblesTest {
 
   @Test
   void handleCollisionsUsingQtTest() {
-    Bubble b1 = new Bubble(10,10,1,3);
+    var b1 = new Bubble(10, 10, 1, 3);
-    Bubble b2 = new Bubble(5,5,2,1);
+    var b2 = new Bubble(5, 5, 2, 1);
-    Bubble b3 = new Bubble(9,9,3,1);
+    var b3 = new Bubble(9, 9, 3, 1);
-    Bubble b4 = new Bubble(8,8,4,2);
+    var b4 = new Bubble(8, 8, 4, 2);
-    Hashtable<Integer, Bubble> bubbles = new Hashtable<Integer, Bubble>();
+    var bubbles = new Hashtable<Integer, Bubble>();
     bubbles.put(1, b1);
     bubbles.put(2, b2);
     bubbles.put(3, b3);
     bubbles.put(4, b4);
-    Rect r = new Rect(10,10,20,20);
+    var r = new Rect(10, 10, 20, 20);
-    QuadTree qt = new QuadTree(r,4);
+    var qt = new QuadTree(r, 4);
     qt.insert(b1);
     qt.insert(b2);
     qt.insert(b3);
     qt.insert(b4);
-    SpatialPartitionBubbles sp = new SpatialPartitionBubbles(bubbles, qt);
+    var sp = new SpatialPartitionBubbles(bubbles, qt);
     sp.handleCollisionsUsingQt(b1);
     //b1 touches b3 and b4 but not b2 - so b1,b3,b4 get popped
-    assertTrue(bubbles.get(1) == null && bubbles.get(2) != null && bubbles.get(3) == null && bubbles.get(4) == null);
+    assertNull(bubbles.get(1));
+    assertNotNull(bubbles.get(2));
+    assertNull(bubbles.get(3));
+    assertNull(bubbles.get(4));
   }
 }

specification/README.md

@@ -100,24 +100,24 @@ public class MassGreaterThanSelector extends AbstractSelector<Creature> {
 With these building blocks in place, we can perform a search for red creatures as follows:
 
 ```java
-    List<Creature> redCreatures = creatures.stream().filter(new ColorSelector(Color.RED))
+    var redCreatures = creatures.stream().filter(new ColorSelector(Color.RED))
       .collect(Collectors.toList());
 ```
 
 But we could also use our parameterized selector like this:
 
 ```java
-    List<Creature> heavyCreatures = creatures.stream().filter(new MassGreaterThanSelector(500.0)
+    var heavyCreatures = creatures.stream().filter(new MassGreaterThanSelector(500.0)
       .collect(Collectors.toList());
 ```
 
 Our third option is to combine multiple selectors together. Performing a search for special creatures (defined as red, flying, and not small) could be done as follows:
 
 ```java
-    AbstractSelector specialCreaturesSelector = 
+    var specialCreaturesSelector = 
       new ColorSelector(Color.RED).and(new MovementSelector(Movement.FLYING)).and(new SizeSelector(Size.SMALL).not());
 
-    List<Creature> specialCreatures = creatures.stream().filter(specialCreaturesSelector)
+    var specialCreatures = creatures.stream().filter(specialCreaturesSelector)
       .collect(Collectors.toList());
 ```
 

specification/src/main/java/com/iluwatar/specification/app/App.java

@@ -32,14 +32,14 @@ import com.iluwatar.specification.creature.Shark;
 import com.iluwatar.specification.creature.Troll;
 import com.iluwatar.specification.property.Color;
 import com.iluwatar.specification.property.Movement;
-import com.iluwatar.specification.selector.AbstractSelector;
 import com.iluwatar.specification.selector.ColorSelector;
 import com.iluwatar.specification.selector.MassEqualSelector;
 import com.iluwatar.specification.selector.MassGreaterThanSelector;
 import com.iluwatar.specification.selector.MassSmallerThanOrEqSelector;
 import com.iluwatar.specification.selector.MovementSelector;
 import java.util.List;
-import java.util.stream.Collectors;
+import java.util.Objects;
+import java.util.function.Predicate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -63,57 +63,47 @@ public class App {
    */
   public static void main(String[] args) {
     // initialize creatures list
-    List<Creature> creatures = List.of(new Goblin(), new Octopus(), new Dragon(), new Shark(),
+    var creatures = List.of(
-        new Troll(), new KillerBee());
+        new Goblin(),
+        new Octopus(),
+        new Dragon(),
+        new Shark(),
+        new Troll(),
+        new KillerBee()
+    );
     // so-called "hard-coded" specification
     LOGGER.info("Demonstrating hard-coded specification :");
     // find all walking creatures
     LOGGER.info("Find all walking creatures");
-    List<Creature> walkingCreatures =
+    print(creatures, new MovementSelector(Movement.WALKING));
-        creatures.stream().filter(new MovementSelector(Movement.WALKING))
-            .collect(Collectors.toList());
-    walkingCreatures.forEach(c -> LOGGER.info(c.toString()));
     // find all dark creatures
     LOGGER.info("Find all dark creatures");
-    List<Creature> darkCreatures =
+    print(creatures, new ColorSelector(Color.DARK));
-        creatures.stream().filter(new ColorSelector(Color.DARK)).collect(Collectors.toList());
-    darkCreatures.forEach(c -> LOGGER.info(c.toString()));
-
     LOGGER.info("\n");
     // so-called "parameterized" specification
     LOGGER.info("Demonstrating parameterized specification :");
     // find all creatures heavier than 500kg
     LOGGER.info("Find all creatures heavier than 600kg");
-    List<Creature> heavyCreatures =
+    print(creatures, new MassGreaterThanSelector(600.0));
-        creatures.stream().filter(new MassGreaterThanSelector(600.0))
-            .collect(Collectors.toList());
-    heavyCreatures.forEach(c -> LOGGER.info(c.toString()));
     // find all creatures heavier than 500kg
     LOGGER.info("Find all creatures lighter than or weighing exactly 500kg");
-    List<Creature> lightCreatures =
+    print(creatures, new MassSmallerThanOrEqSelector(500.0));
-        creatures.stream().filter(new MassSmallerThanOrEqSelector(500.0))
-            .collect(Collectors.toList());
-    lightCreatures.forEach(c -> LOGGER.info(c.toString()));
-
     LOGGER.info("\n");
     // so-called "composite" specification
     LOGGER.info("Demonstrating composite specification :");
     // find all red and flying creatures
     LOGGER.info("Find all red and flying creatures");
-    List<Creature> redAndFlyingCreatures =
+    var redAndFlying = new ColorSelector(Color.RED).and(new MovementSelector(Movement.FLYING));
-        creatures.stream()
+    print(creatures, redAndFlying);
-            .filter(new ColorSelector(Color.RED).and(new MovementSelector(Movement.FLYING)))
-            .collect(Collectors.toList());
-    redAndFlyingCreatures.forEach(c -> LOGGER.info(c.toString()));
     // find all creatures dark or red, non-swimming, and heavier than or equal to 400kg
     LOGGER.info("Find all scary creatures");
-    AbstractSelector<Creature> scaryCreaturesSelector = new ColorSelector(Color.DARK)
+    var scaryCreaturesSelector = new ColorSelector(Color.DARK)
         .or(new ColorSelector(Color.RED)).and(new MovementSelector(Movement.SWIMMING).not())
         .and(new MassGreaterThanSelector(400.0).or(new MassEqualSelector(400.0)));
-    List<Creature> scaryCreatures =
+    print(creatures, scaryCreaturesSelector);
-        creatures.stream()
+  }
-            .filter(scaryCreaturesSelector)
+
-            .collect(Collectors.toList());
+  private static void print(List<? extends Creature> creatures, Predicate<Creature> selector) {
-    scaryCreatures.forEach(c -> LOGGER.info(c.toString()));
+    creatures.stream().filter(selector).map(Objects::toString).forEach(LOGGER::info);
   }
 }

specification/src/test/java/com/iluwatar/specification/app/AppTest.java

@@ -32,7 +32,6 @@ public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

specification/src/test/java/com/iluwatar/specification/creature/CreatureTest.java

@@ -98,12 +98,9 @@ public class CreatureTest {
   @MethodSource("dataProvider")
   public void testToString(Creature testedCreature, String name, Size size, Movement movement,
                            Color color, Mass mass) {
-    final String toString = testedCreature.toString();
+    final var toString = testedCreature.toString();
     assertNotNull(toString);
-    assertEquals(
+    assertEquals(String
-        String.format("%s [size=%s, movement=%s, color=%s, mass=%s]", name, size, movement, color,
+        .format("%s [size=%s, movement=%s, color=%s, mass=%s]", name, size, movement, color, mass), toString);
-            mass),
-        toString
-    );
   }
 }

specification/src/test/java/com/iluwatar/specification/selector/ColorSelectorTest.java

@@ -44,13 +44,13 @@ public class ColorSelectorTest {
    */
   @Test
   public void testColor() {
-    final Creature greenCreature = mock(Creature.class);
+    final var greenCreature = mock(Creature.class);
     when(greenCreature.getColor()).thenReturn(Color.GREEN);
 
-    final Creature redCreature = mock(Creature.class);
+    final var redCreature = mock(Creature.class);
     when(redCreature.getColor()).thenReturn(Color.RED);
 
-    final ColorSelector greenSelector = new ColorSelector(Color.GREEN);
+    final var greenSelector = new ColorSelector(Color.GREEN);
     assertTrue(greenSelector.test(greenCreature));
     assertFalse(greenSelector.test(redCreature));
 

specification/src/test/java/com/iluwatar/specification/selector/CompositeSelectorsTest.java

@@ -40,16 +40,16 @@ public class CompositeSelectorsTest {
    */
   @Test
   public void testAndComposition() {
-    final Creature swimmingHeavyCreature = mock(Creature.class);
+    final var swimmingHeavyCreature = mock(Creature.class);
     when(swimmingHeavyCreature.getMovement()).thenReturn(Movement.SWIMMING);
     when(swimmingHeavyCreature.getMass()).thenReturn(new Mass(100.0));
 
-    final Creature swimmingLightCreature = mock(Creature.class);
+    final var swimmingLightCreature = mock(Creature.class);
     when(swimmingLightCreature.getMovement()).thenReturn(Movement.SWIMMING);
     when(swimmingLightCreature.getMass()).thenReturn(new Mass(25.0));
 
-    final AbstractSelector<Creature> lightAndSwimmingSelector = new MassSmallerThanOrEqSelector(
+    final var lightAndSwimmingSelector = new MassSmallerThanOrEqSelector(50.0)
-        50.0).and(new MovementSelector(Movement.SWIMMING));
+        .and(new MovementSelector(Movement.SWIMMING));
     assertFalse(lightAndSwimmingSelector.test(swimmingHeavyCreature));
     assertTrue(lightAndSwimmingSelector.test(swimmingLightCreature));
   }
@@ -59,15 +59,15 @@ public class CompositeSelectorsTest {
    */
   @Test
   public void testOrComposition() {
-    final Creature swimmingHeavyCreature = mock(Creature.class);
+    final var swimmingHeavyCreature = mock(Creature.class);
     when(swimmingHeavyCreature.getMovement()).thenReturn(Movement.SWIMMING);
     when(swimmingHeavyCreature.getMass()).thenReturn(new Mass(100.0));
 
-    final Creature swimmingLightCreature = mock(Creature.class);
+    final var swimmingLightCreature = mock(Creature.class);
     when(swimmingLightCreature.getMovement()).thenReturn(Movement.SWIMMING);
     when(swimmingLightCreature.getMass()).thenReturn(new Mass(25.0));
 
-    final AbstractSelector<Creature> lightOrSwimmingSelector = new MassSmallerThanOrEqSelector(50.0)
+    final var lightOrSwimmingSelector = new MassSmallerThanOrEqSelector(50.0)
         .or(new MovementSelector(Movement.SWIMMING));
     assertTrue(lightOrSwimmingSelector.test(swimmingHeavyCreature));
     assertTrue(lightOrSwimmingSelector.test(swimmingLightCreature));
@@ -78,15 +78,15 @@ public class CompositeSelectorsTest {
    */
   @Test
   public void testNotComposition() {
-    final Creature swimmingHeavyCreature = mock(Creature.class);
+    final var swimmingHeavyCreature = mock(Creature.class);
     when(swimmingHeavyCreature.getMovement()).thenReturn(Movement.SWIMMING);
     when(swimmingHeavyCreature.getMass()).thenReturn(new Mass(100.0));
 
-    final Creature swimmingLightCreature = mock(Creature.class);
+    final var swimmingLightCreature = mock(Creature.class);
     when(swimmingLightCreature.getMovement()).thenReturn(Movement.SWIMMING);
     when(swimmingLightCreature.getMass()).thenReturn(new Mass(25.0));
 
-    final AbstractSelector<Creature> heavySelector = new MassSmallerThanOrEqSelector(50.0).not();
+    final var heavySelector = new MassSmallerThanOrEqSelector(50.0).not();
     assertTrue(heavySelector.test(swimmingHeavyCreature));
     assertFalse(heavySelector.test(swimmingLightCreature));
   }

specification/src/test/java/com/iluwatar/specification/selector/MassSelectorTest.java

@@ -39,13 +39,13 @@ public class MassSelectorTest {
    */
   @Test
   public void testMass() {
-    final Creature lightCreature = mock(Creature.class);
+    final var lightCreature = mock(Creature.class);
     when(lightCreature.getMass()).thenReturn(new Mass(50.0));
 
-    final Creature heavyCreature = mock(Creature.class);
+    final var heavyCreature = mock(Creature.class);
     when(heavyCreature.getMass()).thenReturn(new Mass(2500.0));
 
-    final MassSmallerThanOrEqSelector lightSelector = new MassSmallerThanOrEqSelector(500.0);
+    final var lightSelector = new MassSmallerThanOrEqSelector(500.0);
     assertTrue(lightSelector.test(lightCreature));
     assertFalse(lightSelector.test(heavyCreature));
   }

specification/src/test/java/com/iluwatar/specification/selector/MovementSelectorTest.java

@@ -44,13 +44,13 @@ public class MovementSelectorTest {
    */
   @Test
   public void testMovement() {
-    final Creature swimmingCreature = mock(Creature.class);
+    final var swimmingCreature = mock(Creature.class);
     when(swimmingCreature.getMovement()).thenReturn(Movement.SWIMMING);
 
-    final Creature flyingCreature = mock(Creature.class);
+    final var flyingCreature = mock(Creature.class);
     when(flyingCreature.getMovement()).thenReturn(Movement.FLYING);
 
-    final MovementSelector swimmingSelector = new MovementSelector(Movement.SWIMMING);
+    final var swimmingSelector = new MovementSelector(Movement.SWIMMING);
     assertTrue(swimmingSelector.test(swimmingCreature));
     assertFalse(swimmingSelector.test(flyingCreature));
 

specification/src/test/java/com/iluwatar/specification/selector/SizeSelectorTest.java

@@ -44,13 +44,13 @@ public class SizeSelectorTest {
    */
   @Test
   public void testMovement() {
-    final Creature normalCreature = mock(Creature.class);
+    final var normalCreature = mock(Creature.class);
     when(normalCreature.getSize()).thenReturn(Size.NORMAL);
 
-    final Creature smallCreature = mock(Creature.class);
+    final var smallCreature = mock(Creature.class);
     when(smallCreature.getSize()).thenReturn(Size.SMALL);
 
-    final SizeSelector normalSelector = new SizeSelector(Size.NORMAL);
+    final var normalSelector = new SizeSelector(Size.NORMAL);
     assertTrue(normalSelector.test(normalCreature));
     assertFalse(normalSelector.test(smallCreature));
   }

state/src/test/java/com/iluwatar/state/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.state;
 import org.junit.jupiter.api.Test;
 
 /**
- *
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

state/src/test/java/com/iluwatar/state/MammothTest.java

@@ -23,20 +23,19 @@
 
 package com.iluwatar.state;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
+import java.util.LinkedList;
+import java.util.List;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.LoggerFactory;
 
-import java.util.LinkedList;
-import java.util.List;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-
 /**
  * Date: 12/29/15 - 8:27 PM
  *
@@ -62,27 +61,27 @@ public class MammothTest {
    */
   @Test
   public void testTimePasses() {
-    final Mammoth mammoth = new Mammoth();
+    final var mammoth = new Mammoth();
 
     mammoth.observe();
     assertEquals("The mammoth is calm and peaceful.", appender.getLastMessage());
-    assertEquals(1 , appender.getLogSize());
+    assertEquals(1, appender.getLogSize());
 
     mammoth.timePasses();
     assertEquals("The mammoth gets angry!", appender.getLastMessage());
-    assertEquals(2 , appender.getLogSize());
+    assertEquals(2, appender.getLogSize());
 
     mammoth.observe();
     assertEquals("The mammoth is furious!", appender.getLastMessage());
-    assertEquals(3 , appender.getLogSize());
+    assertEquals(3, appender.getLogSize());
 
     mammoth.timePasses();
     assertEquals("The mammoth calms down.", appender.getLastMessage());
-    assertEquals(4 , appender.getLogSize());
+    assertEquals(4, appender.getLogSize());
 
     mammoth.observe();
     assertEquals("The mammoth is calm and peaceful.", appender.getLastMessage());
-    assertEquals(5 , appender.getLogSize());
+    assertEquals(5, appender.getLogSize());
 
   }
 
@@ -91,7 +90,7 @@ public class MammothTest {
    */
   @Test
   public void testToString() {
-    final String toString = new Mammoth().toString();
+    final var toString = new Mammoth().toString();
     assertNotNull(toString);
     assertEquals("The mammoth", toString);
   }

step-builder/src/main/java/com/iluwatar/stepbuilder/App.java

@@ -67,21 +67,34 @@ public class App {
    */
   public static void main(String[] args) {
 
-    var warrior =
+    var warrior = CharacterStepBuilder
-        CharacterStepBuilder.newBuilder().name("Amberjill").fighterClass("Paladin")
+        .newBuilder()
-            .withWeapon("Sword").noAbilities().build();
+        .name("Amberjill")
+        .fighterClass("Paladin")
+        .withWeapon("Sword")
+        .noAbilities()
+        .build();
 
     LOGGER.info(warrior.toString());
 
-    var mage =
+    var mage = CharacterStepBuilder
-        CharacterStepBuilder.newBuilder().name("Riobard").wizardClass("Sorcerer")
+        .newBuilder()
-            .withSpell("Fireball").withAbility("Fire Aura").withAbility("Teleport")
+        .name("Riobard")
-            .noMoreAbilities().build();
+        .wizardClass("Sorcerer")
+        .withSpell("Fireball")
+        .withAbility("Fire Aura")
+        .withAbility("Teleport")
+        .noMoreAbilities()
+        .build();
 
     LOGGER.info(mage.toString());
 
-    var thief =
+    var thief = CharacterStepBuilder
-        CharacterStepBuilder.newBuilder().name("Desmond").fighterClass("Rogue").noWeapon().build();
+        .newBuilder()
+        .name("Desmond")
+        .fighterClass("Rogue")
+        .noWeapon()
+        .build();
 
     LOGGER.info(thief.toString());
   }

step-builder/src/main/java/com/iluwatar/stepbuilder/Character.java

@@ -91,15 +91,15 @@ public class Character {
 
   @Override
   public String toString() {
-    var sb = new StringBuilder();
+    return new StringBuilder()
-    sb.append("This is a ")
+        .append("This is a ")
         .append(fighterClass != null ? fighterClass : wizardClass)
         .append(" named ")
         .append(name)
         .append(" armed with a ")
         .append(weapon != null ? weapon : spell != null ? spell : "with nothing")
         .append(abilities != null ? " and wielding " + abilities + " abilities" : "")
-        .append('.');
+        .append('.')
-    return sb.toString();
+        .toString();
   }
 }

step-builder/src/main/java/com/iluwatar/stepbuilder/CharacterStepBuilder.java

@@ -165,7 +165,7 @@ public final class CharacterStepBuilder {
 
     @Override
     public Character build() {
-      Character character = new Character(name);
+      var character = new Character(name);
 
       if (fighterClass != null) {
         character.setFighterClass(fighterClass);

step-builder/src/test/java/com/iluwatar/stepbuilder/AppTest.java

@@ -26,15 +26,12 @@ package com.iluwatar.stepbuilder;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

step-builder/src/test/java/com/iluwatar/stepbuilder/CharacterStepBuilderTest.java

@@ -23,15 +23,13 @@
 
 package com.iluwatar.stepbuilder;
 
-import org.junit.jupiter.api.Test;
-
-import java.util.List;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Date: 12/29/15 - 9:21 PM
  *
@@ -44,7 +42,7 @@ public class CharacterStepBuilderTest {
    */
   @Test
   public void testBuildWizard() {
-    final Character character = CharacterStepBuilder.newBuilder()
+    final var character = CharacterStepBuilder.newBuilder()
         .name("Merlin")
         .wizardClass("alchemist")
         .withSpell("poison")
@@ -58,7 +56,7 @@ public class CharacterStepBuilderTest {
     assertEquals("poison", character.getSpell());
     assertNotNull(character.toString());
 
-    final List<String> abilities = character.getAbilities();
+    final var abilities = character.getAbilities();
     assertNotNull(abilities);
     assertEquals(2, abilities.size());
     assertTrue(abilities.contains("invisibility"));
@@ -72,7 +70,7 @@ public class CharacterStepBuilderTest {
    */
   @Test
   public void testBuildPoorWizard() {
-    final Character character = CharacterStepBuilder.newBuilder()
+    final var character = CharacterStepBuilder.newBuilder()
         .name("Merlin")
         .wizardClass("alchemist")
         .noSpell()
@@ -91,7 +89,7 @@ public class CharacterStepBuilderTest {
    */
   @Test
   public void testBuildWeakWizard() {
-    final Character character = CharacterStepBuilder.newBuilder()
+    final var character = CharacterStepBuilder.newBuilder()
         .name("Merlin")
         .wizardClass("alchemist")
         .withSpell("poison")
@@ -112,7 +110,7 @@ public class CharacterStepBuilderTest {
    */
   @Test
   public void testBuildWarrior() {
-    final Character character = CharacterStepBuilder.newBuilder()
+    final var character = CharacterStepBuilder.newBuilder()
         .name("Cuauhtemoc")
         .fighterClass("aztec")
         .withWeapon("spear")
@@ -126,7 +124,7 @@ public class CharacterStepBuilderTest {
     assertEquals("spear", character.getWeapon());
     assertNotNull(character.toString());
 
-    final List<String> abilities = character.getAbilities();
+    final var abilities = character.getAbilities();
     assertNotNull(abilities);
     assertEquals(2, abilities.size());
     assertTrue(abilities.contains("speed"));
@@ -140,7 +138,7 @@ public class CharacterStepBuilderTest {
    */
   @Test
   public void testBuildPoorWarrior() {
-    final Character character = CharacterStepBuilder.newBuilder()
+    final var character = CharacterStepBuilder.newBuilder()
         .name("Poor warrior")
         .fighterClass("none")
         .noWeapon()
@@ -160,7 +158,7 @@ public class CharacterStepBuilderTest {
    */
   @Test
   public void testBuildWeakWarrior() {
-    final Character character = CharacterStepBuilder.newBuilder()
+    final var character = CharacterStepBuilder.newBuilder()
         .name("Weak warrior")
         .fighterClass("none")
         .withWeapon("Slingshot")

strategy/src/test/java/com/iluwatar/strategy/AppTest.java

@@ -32,7 +32,6 @@ public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

strategy/src/test/java/com/iluwatar/strategy/DragonSlayerTest.java

@@ -41,8 +41,8 @@ public class DragonSlayerTest {
    */
   @Test
   public void testGoToBattle() {
-    final DragonSlayingStrategy strategy = mock(DragonSlayingStrategy.class);
+    final var strategy = mock(DragonSlayingStrategy.class);
-    final DragonSlayer dragonSlayer = new DragonSlayer(strategy);
+    final var dragonSlayer = new DragonSlayer(strategy);
 
     dragonSlayer.goToBattle();
     verify(strategy).execute();
@@ -54,13 +54,13 @@ public class DragonSlayerTest {
    */
   @Test
   public void testChangeStrategy() {
-    final DragonSlayingStrategy initialStrategy = mock(DragonSlayingStrategy.class);
+    final var initialStrategy = mock(DragonSlayingStrategy.class);
-    final DragonSlayer dragonSlayer = new DragonSlayer(initialStrategy);
+    final var dragonSlayer = new DragonSlayer(initialStrategy);
 
     dragonSlayer.goToBattle();
     verify(initialStrategy).execute();
 
-    final DragonSlayingStrategy newStrategy = mock(DragonSlayingStrategy.class);
+    final var newStrategy = mock(DragonSlayingStrategy.class);
     dragonSlayer.changeStrategy(newStrategy);
 
     dragonSlayer.goToBattle();

strategy/src/test/java/com/iluwatar/strategy/DragonSlayingStrategyTest.java

@@ -28,11 +28,9 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
-
 import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
-
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.params.ParameterizedTest;

subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/AppTest.java

@@ -32,7 +32,6 @@ public class AppTest {
 
   @Test
   public void testMain() {
-    String[] args = {};
+    App.main(new String[]{});
-    App.main(args);
   }
 }

subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/GroundDiveTest.java

@@ -70,8 +70,8 @@ public class GroundDiveTest {
   public void testActivate() {
     log.clearLog();
     var groundDive = new GroundDive();
-    groundDive.activate();;
+    groundDive.activate();
-    String[] logs = log.getLog().split("\n");
+    var logs = log.getLog().split("\n");
     final var expectedSize = 3;
     final var log1 = logs[0].split("-")[1].trim() + " -" + logs[0].split("-")[2].trim();
     final var expectedLog1 = "Move to ( 0.0, 0.0, -20.0 )";

subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/SkyLaunchTest.java

@@ -70,8 +70,8 @@ public class SkyLaunchTest {
   public void testActivate() {
     log.clearLog();
     var skyLaunch = new SkyLaunch();
-    skyLaunch.activate();;
+    skyLaunch.activate();
-    String[] logs = log.getLog().split("\n");
+    var logs = log.getLog().split("\n");
     final var expectedSize = 3;
     final var log1 = getLogContent(logs[0]);
     final var expectedLog1 = "Move to ( 0.0, 0.0, 20.0 )";