Updated class diagram PNG

abstract-document/src/test/java/com/iluwatar/abstractdocument/AbstractDocumentTest.java

@@ -32,7 +32,6 @@ import java.util.stream.Stream;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * AbstractDocument test class
@@ -82,8 +81,8 @@ public class AbstractDocumentTest {
     Map<String, Object> props = new HashMap<>();
     props.put(KEY, VALUE);
     DocumentImplementation document = new DocumentImplementation(props);
-    assertTrue(document.toString().contains(KEY));
-    assertTrue(document.toString().contains(VALUE));
+    assertNotNull(document.toString().contains(KEY));
+    assertNotNull(document.toString().contains(VALUE));
   }
 
 }

acyclic-visitor/src/test/java/com/iluwatar/acyclicvisitor/ConfigureForUnixVisitorTest.java

@@ -25,19 +25,27 @@ package com.iluwatar.acyclicvisitor;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.groups.Tuple.tuple;
 import static uk.org.lidalia.slf4jext.Level.INFO;
-
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.Test;
+import static org.mockito.Mockito.mock;
 
 import uk.org.lidalia.slf4jtest.TestLogger;
 import uk.org.lidalia.slf4jtest.TestLoggerFactory;
+import org.junit.jupiter.api.Test;
+
+import com.iluwatar.acyclicvisitor.ConfigureForUnixVisitor;
+import com.iluwatar.acyclicvisitor.Hayes;
+import com.iluwatar.acyclicvisitor.HayesVisitor;
+import com.iluwatar.acyclicvisitor.Zoom;
+import com.iluwatar.acyclicvisitor.ZoomVisitor;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
 
 /**
  * ConfigureForUnixVisitor test class
  */
 public class ConfigureForUnixVisitorTest {
   
-  private static final TestLogger LOGGER = TestLoggerFactory.getTestLogger(ConfigureForUnixVisitor.class);
+  TestLogger logger = TestLoggerFactory.getTestLogger(ConfigureForUnixVisitor.class);
   
   @AfterEach
   public void clearLoggers() {
@@ -51,7 +59,7 @@ public class ConfigureForUnixVisitorTest {
     
     conUnix.visit(zoom);
     
-    assertThat(LOGGER.getLoggingEvents()).extracting("level", "message").contains(
+    assertThat(logger.getLoggingEvents()).extracting("level", "message").contains(
         tuple(INFO, zoom + " used with Unix configurator."));
   }
 }

aggregator-microservices/inventory-microservice/src/test/java/com/iluwatar/inventory/microservice/InventoryControllerTest.java

@@ -31,7 +31,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  */
 public class InventoryControllerTest {
   @Test
-  public void testGetProductInventories() {
+  public void testGetProductInventories() throws Exception {
     InventoryController inventoryController = new InventoryController();
 
     int numberOfInventories = inventoryController.getProductInventories();

bridge/src/test/java/com/iluwatar/bridge/HammerTest.java

@@ -37,7 +37,7 @@ public class HammerTest extends WeaponTest {
    * underlying weapon implementation.
    */
   @Test
-  public void testHammer() {
+  public void testHammer() throws Exception {
     final Hammer hammer = spy(new Hammer(mock(FlyingEnchantment.class)));
     testBasicWeaponActions(hammer);
   }

bridge/src/test/java/com/iluwatar/bridge/SwordTest.java

@@ -37,7 +37,7 @@ public class SwordTest extends WeaponTest {
    * underlying weapon implementation.
    */
   @Test
-  public void testSword() {
+  public void testSword() throws Exception {
     final Sword sword = spy(new Sword(mock(FlyingEnchantment.class)));
     testBasicWeaponActions(sword);
   }

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

@@ -41,7 +41,12 @@ public class App {
    */
   public static void main(String[] args) {
     Task task = new SimpleTask();
-    Callback callback = () -> LOGGER.info("I'm done now.");
+    Callback callback = new Callback() {
+      @Override
+      public void call() {
+        LOGGER.info("I'm done now.");
+      }
+    };
     task.executeWith(callback);
   }
 }

callback/src/test/java/com/iluwatar/callback/CallbackTest.java

@@ -38,6 +38,29 @@ public class CallbackTest {
 
   @Test
   public void test() {
+    Callback callback = new Callback() {
+      @Override
+      public void call() {
+        callingCount++;
+      }
+    };
+
+    Task task = new SimpleTask();
+
+    assertEquals(new Integer(0), callingCount, "Initial calling count of 0");
+
+    task.executeWith(callback);
+
+    assertEquals(new Integer(1), callingCount, "Callback called once");
+
+    task.executeWith(callback);
+
+    assertEquals(new Integer(2), callingCount, "Callback called twice");
+
+  }
+
+  @Test
+  public void testWithLambdasExample() {
     Callback callback = () -> callingCount++;
 
     Task task = new SimpleTask();

chain/src/test/java/com/iluwatar/chain/OrcKingTest.java

@@ -43,7 +43,7 @@ public class OrcKingTest {
   };
 
   @Test
-  public void testMakeRequest() {
+  public void testMakeRequest() throws Exception {
     final OrcKing king = new OrcKing();
 
     for (final Request request : REQUESTS) {

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/Car.java

@@ -26,10 +26,10 @@ package com.iluwatar.collectionpipeline;
  * A Car class that has the properties of make, model, year and category.
  */
 public class Car {
-  private final String make;
-  private final String model;
-  private final int year;
-  private final Category category;
+  private String make;
+  private String model;
+  private int year;
+  private Category category;
 
   /**
    * Constructor to create an instance of car.

converter/src/test/java/com/iluwatar/converter/ConverterTest.java

@@ -71,7 +71,7 @@ public class ConverterTest {
         user.getFirstName().toLowerCase() + user.getLastName().toLowerCase() + "@whatever.com"));
     User u1 = new User("John", "Doe", false, "12324");
     UserDto userDto = converter.convertFromEntity(u1);
-    assertEquals("johndoe@whatever.com", userDto.getEmail());
+    assertEquals(userDto.getEmail(), "johndoe@whatever.com");
   }
 
   /**
@@ -83,6 +83,6 @@ public class ConverterTest {
     ArrayList<User> users = Lists.newArrayList(new User("Camile", "Tough", false, "124sad"),
         new User("Marti", "Luther", true, "42309fd"), new User("Kate", "Smith", true, "if0243"));
     List<User> fromDtos = userConverter.createFromDtos(userConverter.createFromEntities(users));
-    assertEquals(users, fromDtos);
+    assertEquals(fromDtos, users);
   }
 }

cqrs/src/test/java/com/iluwatar/cqrs/IntegrationTest.java

@@ -96,7 +96,7 @@ public class IntegrationTest {
   @Test
   public void testGetAuthorBooks() {
     List<Book> books = queryService.getAuthorBooks("username1");
-    assertEquals(2, books.size());
+    assertTrue(books.size() == 2);
     assertTrue(books.contains(new Book("title1", 10)));
     assertTrue(books.contains(new Book("new_title2", 30)));
   }

dao/src/test/java/com/iluwatar/dao/CustomerTest.java

@@ -88,7 +88,13 @@ public class CustomerTest {
 
   @Test
   public void testToString() {
-    assertEquals(String.format("Customer{id=%s, firstName='%s', lastName='%s'}",
-        customer.getId(), customer.getFirstName(), customer.getLastName()), customer.toString());
+    final StringBuffer buffer = new StringBuffer();
+    buffer.append("Customer{id=")
+            .append("" + customer.getId())
+            .append(", firstName='")
+            .append(customer.getFirstName())
+            .append("\', lastName='")
+            .append(customer.getLastName() + "\'}");
+    assertEquals(buffer.toString(), customer.toString());
   }
 }

dao/src/test/java/com/iluwatar/dao/DbCustomerDaoTest.java

@@ -257,7 +257,7 @@ public class DbCustomerDaoTest {
 
   private void assertCustomerCountIs(int count) throws Exception {
     try (Stream<Customer> allCustomers = dao.getAll()) {
-      assertEquals(count, allCustomers.count());
+      assertTrue(allCustomers.count() == count);
     }
   }
 

dao/src/test/java/com/iluwatar/dao/InMemoryCustomerDaoTest.java

@@ -156,7 +156,7 @@ public class InMemoryCustomerDaoTest {
   
   private void assertCustomerCountIs(int count) throws Exception {
     try (Stream<Customer> allCustomers = dao.getAll()) {
-      assertEquals(count, allCustomers.count());
+      assertTrue(allCustomers.count() == count);
     }
   }
 }

data-mapper/src/test/java/com/iluwatar/datamapper/DataMapperTest.java

@@ -21,7 +21,6 @@ package com.iluwatar.datamapper;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
 
 /**
  * The Data Mapper (DM) is a layer of software that separates the in-memory objects from the
@@ -44,29 +43,27 @@ public class DataMapperTest {
     final StudentDataMapper mapper = new StudentDataMapperImpl();
 
     /* Create new student */
-    int studentId = 1;
-    Student student = new Student(studentId, "Adam", 'A');
+    Student student = new Student(1, "Adam", 'A');
 
     /* Add student in respectibe db */
     mapper.insert(student);
 
     /* Check if student is added in db */
-    assertEquals(studentId, mapper.find(student.getStudentId()).get().getStudentId());
+    assertEquals(student.getStudentId(), mapper.find(student.getStudentId()).get().getStudentId());
 
     /* Update existing student object */
-    String updatedName = "AdamUpdated";
-    student = new Student(student.getStudentId(), updatedName, 'A');
+    student = new Student(student.getStudentId(), "AdamUpdated", 'A');
 
     /* Update student in respectibe db */
     mapper.update(student);
 
     /* Check if student is updated in db */
-    assertEquals(updatedName, mapper.find(student.getStudentId()).get().getName());
+    assertEquals(mapper.find(student.getStudentId()).get().getName(), "AdamUpdated");
 
     /* Delete student in db */
     mapper.delete(student);
 
     /* Result should be false */
-    assertFalse(mapper.find(student.getStudentId()).isPresent());
+    assertEquals(false, mapper.find(student.getStudentId()).isPresent());
   }
 }

data-mapper/src/test/java/com/iluwatar/datamapper/StudentTest.java

@@ -20,9 +20,7 @@ package com.iluwatar.datamapper;
 
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
@@ -30,27 +28,28 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  */
 public final class StudentTest {
 
+  @Test
   /**
    * This API tests the equality behaviour of Student object
    * Object Equality should work as per logic defined in equals method
    *
    * @throws Exception if any execution error during test
    */
-  @Test
   public void testEquality() throws Exception {
 
     /* Create some students */
     final Student firstStudent = new Student(1, "Adam", 'A');
     final Student secondStudent = new Student(2, "Donald", 'B');
     final Student secondSameStudent = new Student(2, "Donald", 'B');
+    final Student firstSameStudent = firstStudent;
 
     /* Check equals functionality: should return 'true' */
-    assertEquals(firstStudent, firstStudent);
+    assertTrue(firstStudent.equals(firstSameStudent));
 
     /* Check equals functionality: should return 'false' */
-    assertNotEquals(firstStudent, secondStudent);
+    assertFalse(firstStudent.equals(secondStudent));
 
     /* Check equals functionality: should return 'true' */
-    assertEquals(secondStudent, secondSameStudent);
+    assertTrue(secondStudent.equals(secondSameStudent));
   }
 }

data-transfer-object/src/test/java/com/iluwatar/datatransfer/CustomerResourceTest.java

@@ -30,7 +30,6 @@ import java.util.ArrayList;
 import java.util.List;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * tests {@link CustomerResource}.
@@ -46,10 +45,10 @@ public class CustomerResourceTest {
 
     List<CustomerDto> allCustomers = customerResource.getAllCustomers();
 
-    assertEquals(1, allCustomers.size());
-    assertEquals("1", allCustomers.get(0).getId());
-    assertEquals("Melody", allCustomers.get(0).getFirstName());
-    assertEquals("Yates", allCustomers.get(0).getLastName());
+    assertEquals(allCustomers.size(), 1);
+    assertEquals(allCustomers.get(0).getId(), "1");
+    assertEquals(allCustomers.get(0).getFirstName(), "Melody");
+    assertEquals(allCustomers.get(0).getLastName(), "Yates");
   }
 
   @Test
@@ -60,9 +59,9 @@ public class CustomerResourceTest {
     customerResource.save(customer);
 
     List<CustomerDto> allCustomers = customerResource.getAllCustomers();
-    assertEquals("1", allCustomers.get(0).getId());
-    assertEquals("Rita", allCustomers.get(0).getFirstName());
-    assertEquals("Reynolds", allCustomers.get(0).getLastName());
+    assertEquals(allCustomers.get(0).getId(), "1");
+    assertEquals(allCustomers.get(0).getFirstName(), "Rita");
+    assertEquals(allCustomers.get(0).getLastName(), "Reynolds");
   }
 
   @Test
@@ -76,7 +75,7 @@ public class CustomerResourceTest {
     customerResource.delete(customer.getId());
 
     List<CustomerDto> allCustomers = customerResource.getAllCustomers();
-    assertTrue(allCustomers.isEmpty());
+    assertEquals(allCustomers.size(), 0);
   }
 
 }

delegation/src/main/java/com/iluwatar/delegation/simple/App.java

@@ -40,7 +40,7 @@ import com.iluwatar.delegation.simple.printers.HpPrinter;
  */
 public class App {
 
-  private static final String MESSAGE_TO_PRINT = "hello world";
+  public static final String MESSAGE_TO_PRINT = "hello world";
 
   /**
    * Program entry point

dirty-flag/src/test/java/org/dirty/flag/DirtyFlagTest.java

@@ -22,7 +22,6 @@
  */
 package org.dirty.flag;
 
-import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.List;
@@ -42,7 +41,7 @@ public class DirtyFlagTest {
   public void testIsDirty() {
     DataFetcher df = new DataFetcher();
     List<String> countries = df.fetch();
-    assertFalse(countries.isEmpty());
+    assertTrue(!countries.isEmpty());
   }
 
   @Test

eip-aggregator/src/main/java/com/iluwatar/eip/aggregator/routes/AggregatorRoute.java

@@ -51,7 +51,7 @@ public class AggregatorRoute extends RouteBuilder {
    * @throws Exception in case of exception during configuration
    */
   @Override
-  public void configure() {
+  public void configure() throws Exception {
     // Main route
     from("{{entry}}").aggregate(constant(true), aggregator)
         .completionSize(3).completionInterval(2000)

eip-message-channel/src/main/java/com/iluwatar/eip/message/channel/App.java

@@ -70,7 +70,7 @@ public class App {
     });
 
     context.start();
-    context.getRoutes().forEach(r -> LOGGER.info(r.toString()));
+    context.getRoutes().stream().forEach(r -> LOGGER.info(r.toString()));
     context.stop();
   }
 }

eip-publish-subscribe/src/main/java/com/iluwatar/eip/publish/subscribe/App.java

@@ -65,7 +65,7 @@ public class App {
     });
     ProducerTemplate template = context.createProducerTemplate();
     context.start();
-    context.getRoutes().forEach(r -> LOGGER.info(r.toString()));
+    context.getRoutes().stream().forEach(r -> LOGGER.info(r.toString()));
     template.sendBody("direct:origin", "Hello from origin");
     context.stop();
   }

event-aggregator/src/test/java/com/iluwatar/event/aggregator/KingJoffreyTest.java

@@ -76,7 +76,7 @@ public class KingJoffreyTest {
   private class InMemoryAppender extends AppenderBase<ILoggingEvent> {
     private List<ILoggingEvent> log = new LinkedList<>();
 
-    public InMemoryAppender(Class<?> clazz) {
+    public InMemoryAppender(Class clazz) {
       ((Logger) LoggerFactory.getLogger(clazz)).addAppender(this);
       start();
     }

event-aggregator/src/test/java/com/iluwatar/event/aggregator/WeekdayTest.java

@@ -35,7 +35,7 @@ import static org.junit.jupiter.api.Assertions.assertNotNull;
 public class WeekdayTest {
 
   @Test
-  public void testToString() {
+  public void testToString() throws Exception {
     for (final Weekday weekday : Weekday.values()) {
       final String toString = weekday.toString();
       assertNotNull(toString);

event-asynchronous/src/test/java/com/iluwatar/event/asynchronous/EventAsynchronousTest.java

@@ -16,12 +16,11 @@
  */
 package com.iluwatar.event.asynchronous;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -31,19 +30,26 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  *
  */
 public class EventAsynchronousTest {
+  App app;
+
   private static final Logger LOGGER = LoggerFactory.getLogger(EventAsynchronousTest.class);
 
+  @BeforeEach
+  public void setUp() {
+    app = new App();
+  }
+
   @Test
   public void testAsynchronousEvent() {
     EventManager eventManager = new EventManager();
     try {
       int aEventId = eventManager.createAsync(60);
       eventManager.start(aEventId);
-      assertEquals(1, eventManager.getEventPool().size());
+      assertTrue(eventManager.getEventPool().size() == 1);
       assertTrue(eventManager.getEventPool().size() < EventManager.MAX_RUNNING_EVENTS);
-      assertEquals(-1, eventManager.numOfCurrentlyRunningSyncEvent());
+      assertTrue(eventManager.numOfCurrentlyRunningSyncEvent() == -1);
       eventManager.cancel(aEventId);
-      assertTrue(eventManager.getEventPool().isEmpty());
+      assertTrue(eventManager.getEventPool().size() == 0);
     } catch (MaxNumOfEventsAllowedException | LongRunningEventException | EventDoesNotExistException e) {
       LOGGER.error(e.getMessage());
     }
@@ -55,11 +61,11 @@ public class EventAsynchronousTest {
     try {
       int sEventId = eventManager.create(60);
       eventManager.start(sEventId);
-      assertEquals(1, eventManager.getEventPool().size());
+      assertTrue(eventManager.getEventPool().size() == 1);
       assertTrue(eventManager.getEventPool().size() < EventManager.MAX_RUNNING_EVENTS);
-      assertNotEquals(-1, eventManager.numOfCurrentlyRunningSyncEvent());
+      assertTrue(eventManager.numOfCurrentlyRunningSyncEvent() != -1);
       eventManager.cancel(sEventId);
-      assertTrue(eventManager.getEventPool().isEmpty());
+      assertTrue(eventManager.getEventPool().size() == 0);
     } catch (MaxNumOfEventsAllowedException | LongRunningEventException | EventDoesNotExistException
         | InvalidOperationException e) {
       LOGGER.error(e.getMessage());
@@ -67,7 +73,7 @@ public class EventAsynchronousTest {
   }
 
   @Test
-  public void testUnsuccessfulSynchronousEvent() {
+  public void testUnsuccessfulSynchronousEvent() throws InvalidOperationException {
     assertThrows(InvalidOperationException.class, () -> {
       EventManager eventManager = new EventManager();
       try {
@@ -88,7 +94,7 @@ public class EventAsynchronousTest {
       int eventTime = 1;
 
       int sEventId = eventManager.create(eventTime);
-      assertEquals(1, eventManager.getEventPool().size());
+      assertTrue(eventManager.getEventPool().size() == 1);
       eventManager.start(sEventId);
 
       long currentTime = System.currentTimeMillis();
@@ -98,7 +104,7 @@ public class EventAsynchronousTest {
       while (System.currentTimeMillis() < endTime) {
       }
 
-      assertTrue(eventManager.getEventPool().isEmpty());
+      assertTrue(eventManager.getEventPool().size() == 0);
 
     } catch (MaxNumOfEventsAllowedException | LongRunningEventException | EventDoesNotExistException
         | InvalidOperationException e) {
@@ -115,7 +121,7 @@ public class EventAsynchronousTest {
       int aEventId1 = eventManager.createAsync(eventTime);
       int aEventId2 = eventManager.createAsync(eventTime);
       int aEventId3 = eventManager.createAsync(eventTime);
-      assertEquals(3, eventManager.getEventPool().size());
+      assertTrue(eventManager.getEventPool().size() == 3);
 
       eventManager.start(aEventId1);
       eventManager.start(aEventId2);
@@ -127,7 +133,7 @@ public class EventAsynchronousTest {
       while (System.currentTimeMillis() < endTime) {
       }
 
-      assertTrue(eventManager.getEventPool().isEmpty());
+      assertTrue(eventManager.getEventPool().size() == 0);
 
     } catch (MaxNumOfEventsAllowedException | LongRunningEventException | EventDoesNotExistException e) {
       LOGGER.error(e.getMessage());

event-queue/src/main/java/com/iluwatar/event/queue/App.java

@@ -47,13 +47,15 @@ public class App {
    * @throws IOException when there is a problem with the audio file loading
    * @throws UnsupportedAudioFileException  when the loaded audio file is unsupported 
    */
-  public static void main(String[] args) throws UnsupportedAudioFileException, IOException {
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
-    Audio.playSound(Audio.getAudioStream("./etc/Closed-Hi-Hat-1.wav"), -8.0f);
+  public static void main(String[] args) throws UnsupportedAudioFileException, IOException, InterruptedException {
+    Audio audio = Audio.getInstance();
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Closed-Hi-Hat-1.wav"), -8.0f);
     
     System.out.println("Press Enter key to stop the program...");
-    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
-    br.read();
-    Audio.stopService();
+    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
+      br.read();
+    }
+    audio.stopService();
   }
 }

event-queue/src/main/java/com/iluwatar/event/queue/Audio.java

@@ -23,6 +23,9 @@
 
 package com.iluwatar.event.queue;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.File;
 import java.io.IOException;
 
@@ -38,49 +41,56 @@ import javax.sound.sampled.UnsupportedAudioFileException;
  *
  */
 public class Audio {
+  private static final Logger LOGGER = LoggerFactory.getLogger(Audio.class);
+  private static final Audio INSTANCE = new Audio();
 
   private static final int MAX_PENDING = 16;
 
-  private static int headIndex;
+  private int headIndex;
 
-  private static int tailIndex;
+  private int tailIndex;
 
-  private static Thread updateThread = null;
+  private volatile Thread updateThread = null;
 
-  private static PlayMessage[] pendingAudio = new PlayMessage[MAX_PENDING];
+  private PlayMessage[] pendingAudio = new PlayMessage[MAX_PENDING];
+
+  // Visible only for testing purposes
+  Audio() {
+
+  }
+
+  public static Audio getInstance() {
+    return INSTANCE;
+  }
 
   /**
-   * This method stops the Update Method's thread. 
+   * This method stops the Update Method's thread and waits till service stops.
    */
-  public static synchronized void stopService() {
+  public synchronized void stopService() throws InterruptedException {
     if (updateThread != null) {
       updateThread.interrupt();
     }
+    updateThread.join();
+    updateThread = null;
   }
   
   /**
    * This method check the Update Method's thread is started.
    * @return boolean
    */
-  public static synchronized boolean isServiceRunning() {
-    if (updateThread != null && updateThread.isAlive() ) {
-      return true;
-    } else {
-      return false;
-    }
+  public synchronized boolean isServiceRunning() {
+    return updateThread != null && updateThread.isAlive();
   }
 
   /**
    * Starts the thread for the Update Method pattern if it was not started previously.
    * Also when the thread is is ready initializes the indexes of the queue 
    */
-  public static void init() {
+  public void init() {
     if (updateThread == null) {
-      updateThread = new Thread(new Runnable() {
-        public void run() {
-          while (!Thread.currentThread().isInterrupted()) {
-            Audio.update();
-          }
+      updateThread = new Thread(() -> {
+        while (!Thread.currentThread().isInterrupted()) {
+          update();
         }
       });
     }
@@ -90,7 +100,7 @@ public class Audio {
   /**
    * This is a synchronized thread starter
    */
-  public static synchronized void startThread() {
+  private synchronized void startThread() {
     if (!updateThread.isAlive()) {
       updateThread.start();
       headIndex = 0;
@@ -103,7 +113,7 @@ public class Audio {
    * @param stream is the AudioInputStream for the method
    * @param volume is the level of the audio's volume 
    */
-  public static void playSound(AudioInputStream stream, float volume) {
+  public void playSound(AudioInputStream stream, float volume) {
     init();
     // Walk the pending requests.
     for (int i = headIndex; i != tailIndex; i = (i + 1) % MAX_PENDING) {
@@ -123,7 +133,7 @@ public class Audio {
    * This method uses the Update Method pattern.
    * It takes the audio from the queue and plays it
    */
-  public static void update() {
+  private void update() {
     // If there are no pending requests, do nothing.
     if (headIndex == tailIndex) {
       return;
@@ -136,13 +146,11 @@ public class Audio {
       clip.open(audioStream);
       clip.start();
     } catch (LineUnavailableException e) {
-      System.err.println("Error occoured while loading the audio: The line is unavailable");
-      e.printStackTrace();
+      LOGGER.trace("Error occoured while loading the audio: The line is unavailable", e);
     } catch (IOException e) {
-      System.err.println("Input/Output error while loading the audio");
-      e.printStackTrace();
+      LOGGER.trace("Input/Output error while loading the audio", e);
     } catch (IllegalArgumentException e) {
-      System.err.println("The system doesn't support the sound: " + e.getMessage());
+      LOGGER.trace("The system doesn't support the sound: " + e.getMessage(), e);
     }
   }
 
@@ -153,7 +161,7 @@ public class Audio {
    * @throws UnsupportedAudioFileException when the audio file is not supported 
    * @throws IOException when the file is not readable
    */
-  public static AudioInputStream getAudioStream(String filePath) 
+  public AudioInputStream getAudioStream(String filePath)
       throws UnsupportedAudioFileException, IOException {
     return AudioSystem.getAudioInputStream(new File(filePath).getAbsoluteFile());
   }
@@ -162,7 +170,7 @@ public class Audio {
    * Returns with the message array of the queue 
    * @return PlayMessage[]
    */
-  public static PlayMessage[] getPendingAudio() {
+  public PlayMessage[] getPendingAudio() {
     return pendingAudio;
   }
 

event-queue/src/test/java/com/iluwatar/event/queue/AudioTest.java

@@ -23,6 +23,7 @@
 
 package com.iluwatar.event.queue;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import javax.sound.sampled.UnsupportedAudioFileException;
@@ -39,6 +40,12 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  */
 public class AudioTest {
 
+  private Audio audio;
+
+  @BeforeEach
+  void createAudioInstance() {
+    audio = new Audio();
+  }
   /**
    * Test here that the playSound method works correctly
    * @throws UnsupportedAudioFileException when the audio file is not supported 
@@ -47,13 +54,15 @@ public class AudioTest {
    */
   @Test
   public void testPlaySound() throws UnsupportedAudioFileException, IOException, InterruptedException {
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.wav"), -10.0f);
     // test that service is started
-    assertTrue(Audio.isServiceRunning());
+    assertTrue(audio.isServiceRunning());
     // adding a small pause to be sure that the sound is ended
     Thread.sleep(5000);
+
+    audio.stopService();
     // test that service is finished
-    assertFalse(!Audio.isServiceRunning());
+    assertFalse(audio.isServiceRunning());
   }
 
   /**
@@ -64,16 +73,18 @@ public class AudioTest {
    */
   @Test
   public void testQueue() throws UnsupportedAudioFileException, IOException, InterruptedException {
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    Audio.playSound(Audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
-    assertTrue(Audio.getPendingAudio().length > 0);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    audio.playSound(audio.getAudioStream("./etc/Bass-Drum-1.aif"), -10.0f);
+    assertTrue(audio.getPendingAudio().length > 0);
     // test that service is started
-    assertTrue(Audio.isServiceRunning());
+    assertTrue(audio.isServiceRunning());
     // adding a small pause to be sure that the sound is ended
     Thread.sleep(10000);
+
+    audio.stopService();
     // test that service is finished
-    assertFalse(!Audio.isServiceRunning());
+    assertFalse(audio.isServiceRunning());
   }
 
 }

event-sourcing/src/main/java/com/iluwatar/event/sourcing/app/App.java

@@ -74,7 +74,7 @@ public class App {
     LOGGER.info("Running the system first time............");
     eventProcessor.reset();
 
-    LOGGER.info("Creating the accounts............");
+    LOGGER.info("Creating th accounts............");
 
     eventProcessor.process(new AccountCreateEvent(
         0, new Date().getTime(), ACCOUNT_OF_DAENERYS, "Daenerys Targaryen"));
@@ -98,7 +98,7 @@ public class App {
     LOGGER.info(AccountAggregate.getAccount(ACCOUNT_OF_DAENERYS).toString());
     LOGGER.info(AccountAggregate.getAccount(ACCOUNT_OF_JON).toString());
 
-    LOGGER.info("At that point system had a shut down, state in memory is cleared............");
+    LOGGER.info("At that point system had a shot down, state in memory is cleared............");
     AccountAggregate.resetState();
 
     LOGGER.info("Recover the system by the events in journal file............");

event-sourcing/src/main/java/com/iluwatar/event/sourcing/event/MoneyTransferEvent.java

@@ -92,7 +92,7 @@ public class MoneyTransferEvent extends DomainEvent {
     }
     Account accountTo = AccountAggregate.getAccount(accountNoTo);
     if (accountTo == null) {
-      throw new RuntimeException("Account not found " + accountNoTo);
+      throw new RuntimeException("Account not found" + accountTo);
     }
 
     accountFrom.handleTransferFromEvent(this);

execute-around/src/test/java/com/iluwatar/execute/around/SimpleFileWriterTest.java

@@ -44,17 +44,26 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 @EnableRuleMigrationSupport
 public class SimpleFileWriterTest {
 
+  /**
+   * Create a temporary folder, used to generate files in during this test
+   */
   @Rule
   public final TemporaryFolder testFolder = new TemporaryFolder();
 
+  /**
+   * Verify if the given writer is not 'null'
+   */
   @Test
   public void testWriterNotNull() throws Exception {
     final File temporaryFile = this.testFolder.newFile();
     new SimpleFileWriter(temporaryFile.getPath(), Assertions::assertNotNull);
   }
 
+  /**
+   * Test if the {@link SimpleFileWriter} creates a file if it doesn't exist
+   */
   @Test
-  public void testCreatesNonExistentFile() throws Exception {
+  public void testNonExistentFile() throws Exception {
     final File nonExistingFile = new File(this.testFolder.getRoot(), "non-existing-file");
     assertFalse(nonExistingFile.exists());
 
@@ -62,8 +71,11 @@ public class SimpleFileWriterTest {
     assertTrue(nonExistingFile.exists());
   }
 
+  /**
+   * Test if the data written to the file writer actually gets in the file
+   */
   @Test
-  public void testContentsAreWrittenToFile() throws Exception {
+  public void testActualWrite() throws Exception {
     final String testMessage = "Test message";
 
     final File temporaryFile = this.testFolder.newFile();
@@ -73,15 +85,17 @@ public class SimpleFileWriterTest {
     assertTrue(Files.lines(temporaryFile.toPath()).allMatch(testMessage::equals));
   }
 
+  /**
+   * Verify if an {@link IOException} during the write ripples through
+   */
   @Test
-  public void testRipplesIoExceptionOccurredWhileWriting() {
-    String message = "Some error";
+  public void testIoException() throws Exception {
     assertThrows(IOException.class, () -> {
       final File temporaryFile = this.testFolder.newFile();
       new SimpleFileWriter(temporaryFile.getPath(), writer -> {
-        throw new IOException(message);
+        throw new IOException("");
       });
-    }, message);
+    });
   }
 
 }

extension-objects/src/main/java/concreteextensions/Commander.java

@@ -32,16 +32,16 @@ import units.CommanderUnit;
  */
 public class Commander implements CommanderExtension {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Commander.class);
-
   private CommanderUnit unit;
 
   public Commander(CommanderUnit commanderUnit) {
     this.unit = commanderUnit;
   }
 
+  final Logger logger = LoggerFactory.getLogger(Commander.class);
+
   @Override
   public void commanderReady() {
-    LOGGER.info("[Commander] " + unit.getName() + " is ready!");
+    logger.info("[Commander] " + unit.getName() + " is ready!");
   }
 }

extension-objects/src/main/java/concreteextensions/Sergeant.java

@@ -32,16 +32,16 @@ import units.SergeantUnit;
  */
 public class Sergeant implements SergeantExtension {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(Sergeant.class);
-
   private SergeantUnit unit;
 
   public Sergeant(SergeantUnit sergeantUnit) {
     this.unit = sergeantUnit;
   }
 
+  final Logger logger = LoggerFactory.getLogger(Sergeant.class);
+
   @Override
   public void sergeantReady() {
-    LOGGER.info("[Sergeant] " + unit.getName() + " is ready! ");
+    logger.info("[Sergeant] " + unit.getName() + " is ready! ");
   }
 }

extension-objects/src/main/java/concreteextensions/Soldier.java

@@ -31,7 +31,6 @@ import units.SoldierUnit;
  * Class defining Soldier
  */
 public class Soldier implements SoldierExtension {
-  private static final Logger LOGGER = LoggerFactory.getLogger(Soldier.class);
 
   private SoldierUnit unit;
 
@@ -39,8 +38,10 @@ public class Soldier implements SoldierExtension {
     this.unit = soldierUnit;
   }
 
+  final Logger logger = LoggerFactory.getLogger(Soldier.class);
+
   @Override
   public void soldierReady() {
-    LOGGER.info("[Solider] " + unit.getName() + "  is ready!");
+    logger.info("[Solider] " + unit.getName() + "  is ready!");
   }
 }

extension-objects/src/test/java/concreteextensions/CommanderTest.java

@@ -30,7 +30,7 @@ import units.CommanderUnit;
  */
 public class CommanderTest {
   @Test
-  public void commanderReady() {
+  public void commanderReady() throws Exception {
     final Commander commander = new Commander(new CommanderUnit("CommanderUnitTest"));
 
     commander.commanderReady();

extension-objects/src/test/java/units/CommanderUnitTest.java

@@ -33,13 +33,13 @@ import static org.junit.jupiter.api.Assertions.assertNull;
  */
 public class CommanderUnitTest {
   @Test
-  public void getUnitExtension() {
+  public void getUnitExtension() throws Exception {
 
     final Unit unit = new CommanderUnit("CommanderUnitName");
 
     assertNull(unit.getUnitExtension("SoldierExtension"));
     assertNull(unit.getUnitExtension("SergeantExtension"));
-    assertNotNull(unit.getUnitExtension("CommanderExtension"));
+    assertNotNull((CommanderExtension) unit.getUnitExtension("CommanderExtension"));
   }
 
 }

extension-objects/src/test/java/units/SergeantUnitTest.java

@@ -33,12 +33,12 @@ import static org.junit.jupiter.api.Assertions.assertNull;
  */
 public class SergeantUnitTest {
   @Test
-  public void getUnitExtension() {
+  public void getUnitExtension() throws Exception {
 
     final Unit unit = new SergeantUnit("SergeantUnitName");
 
     assertNull(unit.getUnitExtension("SoldierExtension"));
-    assertNotNull(unit.getUnitExtension("SergeantExtension"));
+    assertNotNull((SergeantExtension) unit.getUnitExtension("SergeantExtension"));
     assertNull(unit.getUnitExtension("CommanderExtension"));
   }
 

extension-objects/src/test/java/units/SoldierUnitTest.java

@@ -33,11 +33,11 @@ import static org.junit.jupiter.api.Assertions.assertNull;
  */
 public class SoldierUnitTest {
   @Test
-  public void getUnitExtension() {
+  public void getUnitExtension() throws Exception {
 
     final Unit unit = new SoldierUnit("SoldierUnitName");
 
-    assertNotNull(unit.getUnitExtension("SoldierExtension"));
+    assertNotNull((SoldierExtension) unit.getUnitExtension("SoldierExtension"));
     assertNull(unit.getUnitExtension("SergeantExtension"));
     assertNull(unit.getUnitExtension("CommanderExtension"));
 

factory-kit/src/test/java/com/iluwatar/factorykit/factorykit/FactoryKitTest.java

@@ -83,7 +83,7 @@ public class FactoryKitTest {
    * @param weapon weapon object which is to be verified
    * @param clazz  expected class of the weapon
    */
-  private void verifyWeapon(Weapon weapon, Class<?> clazz) {
+  private void verifyWeapon(Weapon weapon, Class clazz) {
     assertTrue(clazz.isInstance(weapon), "Weapon must be an object of: " + clazz.getName());
   }
 }

feature-toggle/src/test/java/com/iluwatar/featuretoggle/pattern/propertiesversion/PropertiesFeatureToggleVersionTest.java

@@ -40,14 +40,14 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 public class PropertiesFeatureToggleVersionTest {
 
   @Test
-  public void testNullPropertiesPassed() {
+  public void testNullPropertiesPassed() throws Exception {
     assertThrows(IllegalArgumentException.class, () -> {
       new PropertiesFeatureToggleVersion(null);
     });
   }
 
   @Test
-  public void testNonBooleanProperty() {
+  public void testNonBooleanProperty() throws Exception {
     assertThrows(IllegalArgumentException.class, () -> {
       final Properties properties = new Properties();
       properties.setProperty("enhancedWelcome", "Something");
@@ -56,7 +56,7 @@ public class PropertiesFeatureToggleVersionTest {
   }
 
   @Test
-  public void testFeatureTurnedOn() {
+  public void testFeatureTurnedOn() throws Exception {
     final Properties properties = new Properties();
     properties.put("enhancedWelcome", true);
     Service service = new PropertiesFeatureToggleVersion(properties);
@@ -66,7 +66,7 @@ public class PropertiesFeatureToggleVersionTest {
   }
 
   @Test
-  public void testFeatureTurnedOff() {
+  public void testFeatureTurnedOff() throws Exception {
     final Properties properties = new Properties();
     properties.put("enhancedWelcome", false);
     Service service = new PropertiesFeatureToggleVersion(properties);

feature-toggle/src/test/java/com/iluwatar/featuretoggle/pattern/tieredversion/TieredFeatureToggleVersionTest.java

@@ -41,27 +41,27 @@ public class TieredFeatureToggleVersionTest {
   final Service service = new TieredFeatureToggleVersion();
 
   @BeforeEach
-  public void setUp() {
+  public void setUp() throws Exception {
     UserGroup.addUserToPaidGroup(paidUser);
     UserGroup.addUserToFreeGroup(freeUser);
   }
 
   @Test
-  public void testGetWelcomeMessageForPaidUser() {
+  public void testGetWelcomeMessageForPaidUser() throws Exception {
     final String welcomeMessage = service.getWelcomeMessage(paidUser);
     final String expected = "You're amazing Jamie Coder. Thanks for paying for this awesome software.";
     assertEquals(expected, welcomeMessage);
   }
 
   @Test
-  public void testGetWelcomeMessageForFreeUser() {
+  public void testGetWelcomeMessageForFreeUser() throws Exception {
     final String welcomeMessage = service.getWelcomeMessage(freeUser);
     final String expected = "I suppose you can use this software.";
     assertEquals(expected, welcomeMessage);
   }
 
   @Test
-  public void testIsEnhancedAlwaysTrueAsTiered() {
+  public void testIsEnhancedAlwaysTrueAsTiered() throws Exception {
     assertTrue(service.isEnhanced());
   }
 }

fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/simple/SimpleFluentIterable.java

@@ -171,11 +171,11 @@ public class SimpleFluentIterable<E> implements FluentIterable<E> {
   /**
    * @return a FluentIterable from a given iterable. Calls the SimpleFluentIterable constructor.
    */
-  public static <E> FluentIterable<E> from(Iterable<E> iterable) {
+  public static final <E> FluentIterable<E> from(Iterable<E> iterable) {
     return new SimpleFluentIterable<>(iterable);
   }
 
-  public static <E> FluentIterable<E> fromCopyOf(Iterable<E> iterable) {
+  public static final <E> FluentIterable<E> fromCopyOf(Iterable<E> iterable) {
     List<E> copy = FluentIterable.copyToList(iterable);
     return new SimpleFluentIterable<>(copy);
   }

fluentinterface/src/test/java/com/iluwatar/fluentinterface/fluentiterable/FluentIterableTest.java

@@ -179,15 +179,15 @@ public abstract class FluentIterableTest {
   }
 
   @Test
-  public void testForEach() {
+  public void testForEach() throws Exception {
     final List<Integer> integers = Arrays.asList(1, 2, 3);
 
     final Consumer<Integer> consumer = mock(Consumer.class);
     createFluentIterable(integers).forEach(consumer);
 
-    verify(consumer, times(1)).accept(1);
-    verify(consumer, times(1)).accept(2);
-    verify(consumer, times(1)).accept(3);
+    verify(consumer, times(1)).accept(Integer.valueOf(1));
+    verify(consumer, times(1)).accept(Integer.valueOf(2));
+    verify(consumer, times(1)).accept(Integer.valueOf(3));
     verifyNoMoreInteractions(consumer);
 
   }

front-controller/src/main/java/com/iluwatar/front/controller/FrontController.java

@@ -36,7 +36,7 @@ public class FrontController {
   }
 
   private Command getCommand(String request) {
-    Class<?> commandClass = getCommandClass(request);
+    Class commandClass = getCommandClass(request);
     try {
       return (Command) commandClass.newInstance();
     } catch (Exception e) {
@@ -44,8 +44,8 @@ public class FrontController {
     }
   }
 
-  private static Class<?> getCommandClass(String request) {
-    Class<?> result;
+  private static Class getCommandClass(String request) {
+    Class result;
     try {
       result = Class.forName("com.iluwatar.front.controller." + request + "Command");
     } catch (ClassNotFoundException e) {

front-controller/src/test/java/com/iluwatar/front/controller/ApplicationExceptionTest.java

@@ -34,7 +34,7 @@ import static org.junit.jupiter.api.Assertions.assertSame;
 public class ApplicationExceptionTest {
 
   @Test
-  public void testCause() {
+  public void testCause() throws Exception {
     final Exception cause = new Exception();
     assertSame(cause, new ApplicationException(cause).getCause());
   }

guarded-suspension/src/test/java/com/iluwatar/guarded/suspension/GuardedQueueTest.java

@@ -41,7 +41,7 @@ public class GuardedQueueTest {
     GuardedQueue g = new GuardedQueue();
     ExecutorService executorService = Executors.newFixedThreadPool(2);
     executorService.submit(() -> value = g.get());
-    executorService.submit(() -> g.put(10));
+    executorService.submit(() -> g.put(Integer.valueOf(10)));
     executorService.shutdown();
     try {
       executorService.awaitTermination(30, TimeUnit.SECONDS);

half-sync-half-async/src/test/java/com/iluwatar/halfsynchalfasync/AppTest.java

@@ -34,7 +34,7 @@ import java.util.concurrent.ExecutionException;
 public class AppTest {
 
   @Test
-  public void test() {
+  public void test() throws InterruptedException, ExecutionException {
     App.main(null);
   }
 }

half-sync-half-async/src/test/java/com/iluwatar/halfsynchalfasync/AsynchronousServiceTest.java

@@ -22,7 +22,6 @@
  */
 package com.iluwatar.halfsynchalfasync;
 
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 
@@ -45,17 +44,11 @@ import static org.mockito.Mockito.when;
  * @author Jeroen Meulemeester
  */
 public class AsynchronousServiceTest {
-  private AsynchronousService service;
-  private AsyncTask<Object> task;
-
-  @BeforeEach
-  public void setUp() {
-    service = new AsynchronousService(new LinkedBlockingQueue<>());
-    task = mock(AsyncTask.class);
-  }
 
   @Test
   public void testPerfectExecution() throws Exception {
+    final AsynchronousService service = new AsynchronousService(new LinkedBlockingQueue<>());
+    final AsyncTask<Object> task = mock(AsyncTask.class);
     final Object result = new Object();
     when(task.call()).thenReturn(result);
     service.execute(task);
@@ -72,6 +65,8 @@ public class AsynchronousServiceTest {
 
   @Test
   public void testCallException() throws Exception {
+    final AsynchronousService service = new AsynchronousService(new LinkedBlockingQueue<>());
+    final AsyncTask<Object> task = mock(AsyncTask.class);
     final IOException exception = new IOException();
     when(task.call()).thenThrow(exception);
     service.execute(task);
@@ -87,7 +82,9 @@ public class AsynchronousServiceTest {
   }
 
   @Test
-  public void testPreCallException() {
+  public void testPreCallException() throws Exception {
+    final AsynchronousService service = new AsynchronousService(new LinkedBlockingQueue<>());
+    final AsyncTask<Object> task = mock(AsyncTask.class);
     final IllegalStateException exception = new IllegalStateException();
     doThrow(exception).when(task).onPreCall();
     service.execute(task);

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Client.java

@@ -22,6 +22,9 @@
  */
 package com.iluwatar.intercepting.filter;
 
+import java.awt.BorderLayout;
+import java.awt.GridLayout;
+
 import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JLabel;
@@ -30,9 +33,6 @@ import javax.swing.JRootPane;
 import javax.swing.JTextArea;
 import javax.swing.JTextField;
 import javax.swing.SwingUtilities;
-import javax.swing.WindowConstants;
-import java.awt.BorderLayout;
-import java.awt.GridLayout;
 
 /**
  * The Client class is responsible for handling the input and running them through filters inside the
@@ -60,7 +60,7 @@ public class Client extends JFrame { // NOSONAR
    */
   public Client() {
     super("Client System");
-    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
+    setDefaultCloseOperation(EXIT_ON_CLOSE);
     setSize(300, 300);
     jl = new JLabel("RUNNING...");
     jtFields = new JTextField[3];

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Target.java

@@ -22,6 +22,11 @@
  */
 package com.iluwatar.intercepting.filter;
 
+import java.awt.BorderLayout;
+import java.awt.Dimension;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+
 import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JPanel;
@@ -29,12 +34,7 @@ import javax.swing.JRootPane;
 import javax.swing.JScrollPane;
 import javax.swing.JTable;
 import javax.swing.SwingUtilities;
-import javax.swing.WindowConstants;
 import javax.swing.table.DefaultTableModel;
-import java.awt.BorderLayout;
-import java.awt.Dimension;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 
 /**
  * This is where the requests are displayed after being validated by filters.
@@ -47,6 +47,7 @@ public class Target extends JFrame { //NOSONAR
   private static final long serialVersionUID = 1L;
 
   private JTable jt;
+  private JScrollPane jsp;
   private DefaultTableModel dtm;
   private JButton del;
 
@@ -55,7 +56,7 @@ public class Target extends JFrame { //NOSONAR
    */
   public Target() {
     super("Order System");
-    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
+    setDefaultCloseOperation(EXIT_ON_CLOSE);
     setSize(640, 480);
     dtm =
         new DefaultTableModel(new Object[] {"Name", "Contact Number", "Address", "Deposit Number",
@@ -72,7 +73,7 @@ public class Target extends JFrame { //NOSONAR
     bot.setLayout(new BorderLayout());
     bot.add(del, BorderLayout.EAST);
     add(bot, BorderLayout.SOUTH);
-    JScrollPane jsp = new JScrollPane(jt);
+    jsp = new JScrollPane(jt);
     jsp.setPreferredSize(new Dimension(500, 250));
     add(jsp, BorderLayout.CENTER);
 

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/FilterManagerTest.java

@@ -40,7 +40,7 @@ import static org.mockito.Mockito.when;
 public class FilterManagerTest {
 
   @Test
-  public void testFilterRequest() {
+  public void testFilterRequest() throws Exception {
     final Target target = mock(Target.class);
     final FilterManager filterManager = new FilterManager();
     assertEquals("RUNNING...", filterManager.filterRequest(mock(Order.class)));
@@ -48,7 +48,7 @@ public class FilterManagerTest {
   }
 
   @Test
-  public void testAddFilter() {
+  public void testAddFilter() throws Exception {
     final Target target = mock(Target.class);
     final FilterManager filterManager = new FilterManager();
 

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/FilterTest.java

@@ -89,7 +89,7 @@ public class FilterTest {
 
   @ParameterizedTest
   @MethodSource("getTestData")
-  public void testExecute(Filter filter, Order order, String expectedResult) {
+  public void testExecute(Filter filter, Order order, String expectedResult) throws Exception {
     final String result = filter.execute(order);
     assertNotNull(result);
     assertEquals(expectedResult, result.trim());
@@ -97,7 +97,7 @@ public class FilterTest {
 
   @ParameterizedTest
   @MethodSource("getTestData")
-  public void testNext(Filter filter) {
+  public void testNext(Filter filter) throws Exception {
     assertNull(filter.getNext());
     assertSame(filter, filter.getLast());
   }

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/OrderTest.java

@@ -36,35 +36,35 @@ public class OrderTest {
   private static final String EXPECTED_VALUE = "test";
 
   @Test
-  public void testSetName() {
+  public void testSetName() throws Exception {
     final Order order = new Order();
     order.setName(EXPECTED_VALUE);
     assertEquals(EXPECTED_VALUE, order.getName());
   }
 
   @Test
-  public void testSetContactNumber() {
+  public void testSetContactNumber() throws Exception {
     final Order order = new Order();
     order.setContactNumber(EXPECTED_VALUE);
     assertEquals(EXPECTED_VALUE, order.getContactNumber());
   }
 
   @Test
-  public void testSetAddress() {
+  public void testSetAddress() throws Exception {
     final Order order = new Order();
     order.setAddress(EXPECTED_VALUE);
     assertEquals(EXPECTED_VALUE, order.getAddress());
   }
 
   @Test
-  public void testSetDepositNumber() {
+  public void testSetDepositNumber() throws Exception {
     final Order order = new Order();
     order.setDepositNumber(EXPECTED_VALUE);
     assertEquals(EXPECTED_VALUE, order.getDepositNumber());
   }
 
   @Test
-  public void testSetOrder() {
+  public void testSetOrder() throws Exception {
     final Order order = new Order();
     order.setOrderItem(EXPECTED_VALUE);
     assertEquals(EXPECTED_VALUE, order.getOrderItem());

iterator/src/test/java/com/iluwatar/iterator/bst/BstIteratorTest.java

@@ -50,49 +50,49 @@ class BstIteratorTest {
 
   @Test
   void nextForEmptyTree() {
-    BstIterator<Integer> iter = new BstIterator<>(emptyRoot);
+    BstIterator iter = new BstIterator<>(emptyRoot);
     assertThrows(NoSuchElementException.class, iter::next,
         "next() should throw an IllegalStateException if hasNext() is false.");
   }
 
   @Test
   void nextOverEntirePopulatedTree() {
-    BstIterator<Integer> iter = new BstIterator<>(nonEmptyRoot);
-    assertEquals(Integer.valueOf(1), iter.next().getVal(), "First Node is 1.");
-    assertEquals(Integer.valueOf(3), iter.next().getVal(), "Second Node is 3.");
-    assertEquals(Integer.valueOf(4), iter.next().getVal(), "Third Node is 4.");
-    assertEquals(Integer.valueOf(5), iter.next().getVal(), "Fourth Node is 5.");
-    assertEquals(Integer.valueOf(6), iter.next().getVal(), "Fifth Node is 6.");
-    assertEquals(Integer.valueOf(7), iter.next().getVal(), "Sixth Node is 7.");
+    BstIterator iter = new BstIterator<>(nonEmptyRoot);
+    assertEquals(1, iter.next().getVal(), "First Node is 1.");
+    assertEquals(3, iter.next().getVal(), "Second Node is 3.");
+    assertEquals(4, iter.next().getVal(), "Third Node is 4.");
+    assertEquals(5, iter.next().getVal(), "Fourth Node is 5.");
+    assertEquals(6, iter.next().getVal(), "Fifth Node is 6.");
+    assertEquals(7, iter.next().getVal(), "Sixth Node is 7.");
   }
 
   @Test
   void hasNextForEmptyTree() {
-    BstIterator<Integer> iter = new BstIterator<>(emptyRoot);
+    BstIterator iter = new BstIterator<>(emptyRoot);
     assertFalse(iter.hasNext(), "hasNext() should return false for empty tree.");
   }
 
   @Test
   void hasNextForPopulatedTree() {
-    BstIterator<Integer> iter = new BstIterator<>(nonEmptyRoot);
+    BstIterator iter = new BstIterator<>(nonEmptyRoot);
     assertTrue(iter.hasNext(), "hasNext() should return true for populated tree.");
   }
 
   @Test
   void nextAndHasNextOverEntirePopulatedTree() {
-    BstIterator<Integer> iter = new BstIterator<>(nonEmptyRoot);
+    BstIterator iter = new BstIterator<>(nonEmptyRoot);
     assertTrue(iter.hasNext(), "Iterator hasNext() should be true.");
-    assertEquals(Integer.valueOf(1), iter.next().getVal(), "First Node is 1.");
+    assertEquals(1, iter.next().getVal(), "First Node is 1.");
     assertTrue(iter.hasNext(), "Iterator hasNext() should be true.");
-    assertEquals(Integer.valueOf(3), iter.next().getVal(), "Second Node is 3.");
+    assertEquals(3, iter.next().getVal(), "Second Node is 3.");
     assertTrue(iter.hasNext(), "Iterator hasNext() should be true.");
-    assertEquals(Integer.valueOf(4), iter.next().getVal(), "Third Node is 4.");
+    assertEquals(4, iter.next().getVal(), "Third Node is 4.");
     assertTrue(iter.hasNext(), "Iterator hasNext() should be true.");
-    assertEquals(Integer.valueOf(5), iter.next().getVal(), "Fourth Node is 5.");
+    assertEquals(5, iter.next().getVal(), "Fourth Node is 5.");
     assertTrue(iter.hasNext(), "Iterator hasNext() should be true.");
-    assertEquals(Integer.valueOf(6), iter.next().getVal(), "Fifth Node is 6.");
+    assertEquals(6, iter.next().getVal(), "Fifth Node is 6.");
     assertTrue(iter.hasNext(), "Iterator hasNext() should be true.");
-    assertEquals(Integer.valueOf(7), iter.next().getVal(), "Sixth Node is 7.");
+    assertEquals(7, iter.next().getVal(), "Sixth Node is 7.");
     assertFalse(iter.hasNext(), "Iterator hasNext() should be false, end of tree.");
   }
 

layers/src/main/java/com/iluwatar/layers/CakeViewImpl.java

@@ -41,6 +41,6 @@ public class CakeViewImpl implements View {
   }
 
   public void render() {
-    cakeBakingService.getAllCakes().forEach(cake -> LOGGER.info(cake.toString()));
+    cakeBakingService.getAllCakes().stream().forEach(cake -> LOGGER.info(cake.toString()));
   }
 }

layers/src/test/java/com/iluwatar/layers/CakeBakingExceptionTest.java

@@ -35,14 +35,14 @@ import static org.junit.jupiter.api.Assertions.assertNull;
 public class CakeBakingExceptionTest {
 
   @Test
-  public void testConstructor() {
+  public void testConstructor() throws Exception {
     final CakeBakingException exception = new CakeBakingException();
     assertNull(exception.getMessage());
     assertNull(exception.getCause());
   }
 
   @Test
-  public void testConstructorWithMessage() {
+  public void testConstructorWithMessage() throws Exception {
     final String expectedMessage = "message";
     final CakeBakingException exception = new CakeBakingException(expectedMessage);
     assertEquals(expectedMessage, exception.getMessage());

layers/src/test/java/com/iluwatar/layers/CakeBakingServiceImplTest.java

@@ -42,7 +42,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 public class CakeBakingServiceImplTest {
 
   @Test
-  public void testLayers() {
+  public void testLayers() throws CakeBakingException {
     final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
 
     final List<CakeLayerInfo> initialLayers = service.getAvailableLayers();
@@ -65,7 +65,7 @@ public class CakeBakingServiceImplTest {
   }
 
   @Test
-  public void testToppings() {
+  public void testToppings() throws CakeBakingException {
     final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
 
     final List<CakeToppingInfo> initialToppings = service.getAvailableToppings();
@@ -125,7 +125,7 @@ public class CakeBakingServiceImplTest {
   }
 
   @Test
-  public void testBakeCakeMissingTopping() {
+  public void testBakeCakeMissingTopping() throws CakeBakingException {
     final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
 
     final CakeLayerInfo layer1 = new CakeLayerInfo("Layer1", 1000);
@@ -140,7 +140,7 @@ public class CakeBakingServiceImplTest {
   }
 
   @Test
-  public void testBakeCakeMissingLayer() {
+  public void testBakeCakeMissingLayer() throws CakeBakingException {
     final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
 
     final List<CakeInfo> initialCakes = service.getAllCakes();

layers/src/test/java/com/iluwatar/layers/CakeTest.java

@@ -44,7 +44,7 @@ public class CakeTest {
     final Cake cake = new Cake();
     assertNull(cake.getId());
 
-    final Long expectedId = 1234L;
+    final Long expectedId = Long.valueOf(1234L);
     cake.setId(expectedId);
     assertEquals(expectedId, cake.getId());
   }

lazy-loading/src/main/java/com/iluwatar/lazy/loading/Java8Holder.java

@@ -37,7 +37,7 @@ public class Java8Holder {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(Java8Holder.class);
 
-  private Supplier<Heavy> heavy = this::createAndCacheHeavy;
+  private Supplier<Heavy> heavy = () -> createAndCacheHeavy();
 
   public Java8Holder() {
     LOGGER.info("Java8Holder created");

module/src/test/java/com/iluwatar/module/FileLoggerModuleTest.java

@@ -27,7 +27,6 @@ import java.io.FileReader;
 import java.io.IOException;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNull;
 
 /**
  * The Module pattern can be considered a Creational pattern and a Structural pattern. It manages
@@ -89,7 +88,7 @@ public final class FileLoggerModuleTest {
     fileLoggerModule.prepare();
 
     /* Test if nothing is printed in file */
-    assertNull(readFirstLine(OUTPUT_FILE));
+    assertEquals(readFirstLine(OUTPUT_FILE), null);
 
     /* Unprepare to cleanup the modules */
     fileLoggerModule.unprepare();
@@ -114,7 +113,7 @@ public final class FileLoggerModuleTest {
     fileLoggerModule.printErrorString(ERROR);
 
     /* Test if 'Message' is printed in file */
-    assertEquals(ERROR, readFirstLine(ERROR_FILE));
+    assertEquals(readFirstLine(ERROR_FILE), ERROR);
 
     /* Unprepare to cleanup the modules */
     fileLoggerModule.unprepare();
@@ -136,7 +135,7 @@ public final class FileLoggerModuleTest {
     fileLoggerModule.prepare();
 
     /* Test if nothing is printed in file */
-    assertNull(readFirstLine(ERROR_FILE));
+    assertEquals(readFirstLine(ERROR_FILE), null);
 
     /* Unprepare to cleanup the modules */
     fileLoggerModule.unprepare();
@@ -151,7 +150,11 @@ public final class FileLoggerModuleTest {
   private static final String readFirstLine(final String file) {
 
     String firstLine = null;
-    try (BufferedReader bufferedReader = new BufferedReader(new FileReader(file))) {
+    BufferedReader bufferedReader = null;
+    try {
+
+      /* Create a buffered reader */
+      bufferedReader = new BufferedReader(new FileReader(file));
 
       while (bufferedReader.ready()) {
 
@@ -163,6 +166,15 @@ public final class FileLoggerModuleTest {
 
     } catch (final IOException e) {
       LOGGER.error("ModuleTest::readFirstLine()", e);
+    } finally {
+
+      if (bufferedReader != null) {
+        try {
+          bufferedReader.close();
+        } catch (final IOException e) {
+          LOGGER.error("ModuleTest::readFirstLine()", e);
+        }
+      }
     }
 
     return firstLine;

monostate/src/main/java/com/iluwatar/monostate/LoadBalancer.java

@@ -34,31 +34,33 @@ import java.util.List;
  */
 
 public class LoadBalancer {
-  private static final List<Server> SERVERS = new ArrayList<>();
+  private static List<Server> servers = new ArrayList<>();
   private static int lastServedId;
 
   static {
     int id = 0;
-    for (int port : new int[] {8080, 8081, 8082, 8083, 8084}) {
-      SERVERS.add(new Server("localhost", port, ++id));
-    }
+    servers.add(new Server("localhost", 8081, ++id));
+    servers.add(new Server("localhost", 8080, ++id));
+    servers.add(new Server("localhost", 8082, ++id));
+    servers.add(new Server("localhost", 8083, ++id));
+    servers.add(new Server("localhost", 8084, ++id));
   }
 
   /**
    * Add new server
    */
   public final void addServer(Server server) {
-    synchronized (SERVERS) {
-      SERVERS.add(server);
+    synchronized (servers) {
+      servers.add(server);
     }
 
   }
 
   public final int getNoOfServers() {
-    return SERVERS.size();
+    return servers.size();
   }
 
-  public int getLastServedId() {
+  public static int getLastServedId() {
     return lastServedId;
   }
 
@@ -66,10 +68,10 @@ public class LoadBalancer {
    * Handle request
    */
   public synchronized void serverRequest(Request request) {
-    if (lastServedId >= SERVERS.size()) {
+    if (lastServedId >= servers.size()) {
       lastServedId = 0;
     }
-    Server server = SERVERS.get(lastServedId++);
+    Server server = servers.get(lastServedId++);
     server.serve(request);
   }
   

monostate/src/test/java/com/iluwatar/monostate/LoadBalancerTest.java

@@ -22,7 +22,9 @@
  */
 package com.iluwatar.monostate;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.mock;
@@ -32,8 +34,6 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.when;
 
-import org.junit.jupiter.api.Test;
-
 /**
  * Date: 12/21/15 - 12:26 PM
  *
@@ -47,9 +47,9 @@ public class LoadBalancerTest {
     final LoadBalancer secondBalancer = new LoadBalancer();
     firstBalancer.addServer(new Server("localhost", 8085, 6));
     // Both should have the same number of servers.
-    assertEquals(firstBalancer.getNoOfServers(), secondBalancer.getNoOfServers());
+    assertTrue(firstBalancer.getNoOfServers() == secondBalancer.getNoOfServers());
     // Both Should have the same LastServedId
-    assertEquals(firstBalancer.getLastServedId(), secondBalancer.getLastServedId());
+    assertTrue(firstBalancer.getLastServedId() == secondBalancer.getLastServedId());
   }
 
   @Test

mute-idiom/src/test/java/com/iluwatar/mute/MuteTest.java

@@ -45,27 +45,27 @@ public class MuteTest {
 
   @Test
   public void muteShouldRunTheCheckedRunnableAndNotThrowAnyExceptionIfCheckedRunnableDoesNotThrowAnyException() {
-    Mute.mute(this::methodNotThrowingAnyException);
+    Mute.mute(() -> methodNotThrowingAnyException());
   }
 
   @Test
-  public void muteShouldRethrowUnexpectedExceptionAsAssertionError() {
+  public void muteShouldRethrowUnexpectedExceptionAsAssertionError() throws Exception {
     assertThrows(AssertionError.class, () -> {
-      Mute.mute(this::methodThrowingException);
+      Mute.mute(() -> methodThrowingException());
     });
   }
 
   @Test
   public void loggedMuteShouldRunTheCheckedRunnableAndNotThrowAnyExceptionIfCheckedRunnableDoesNotThrowAnyException() {
-    Mute.loggedMute(this::methodNotThrowingAnyException);
+    Mute.loggedMute(() -> methodNotThrowingAnyException());
   }
 
   @Test
-  public void loggedMuteShouldLogExceptionTraceBeforeSwallowingIt() {
+  public void loggedMuteShouldLogExceptionTraceBeforeSwallowingIt() throws IOException {
     ByteArrayOutputStream stream = new ByteArrayOutputStream();
     System.setErr(new PrintStream(stream));
 
-    Mute.loggedMute(this::methodThrowingException);
+    Mute.loggedMute(() -> methodThrowingException());
 
     assertTrue(new String(stream.toByteArray()).contains(MESSAGE));
   }

null-object/src/test/java/com/iluwatar/nullobject/NullNodeTest.java

@@ -56,7 +56,7 @@ public class NullNodeTest {
   }
 
   @Test
-  public void testWalk() {
+  public void testWalk() throws Exception {
     NullNode.getInstance().walk();
   }
 

null-object/src/test/java/com/iluwatar/nullobject/TreeTest.java

@@ -110,7 +110,7 @@ public class TreeTest {
   }
 
   @Test
-  public void testGetLeft() {
+  public void testGetLeft() throws Exception {
     final Node level1 = TREE_ROOT.getLeft();
     assertNotNull(level1);
     assertEquals("level1_a", level1.getName());
@@ -130,7 +130,7 @@ public class TreeTest {
   }
 
   @Test
-  public void testGetRight() {
+  public void testGetRight() throws Exception {
     final Node level1 = TREE_ROOT.getRight();
     assertNotNull(level1);
     assertEquals("level1_b", level1.getName());

object-mother/src/main/java/com/iluwatar/objectmother/King.java

@@ -59,7 +59,7 @@ public class King implements Royalty {
    */
   public void flirt(Queen queen) {
     boolean flirtStatus = queen.getFlirted(this);
-    if (!flirtStatus) {
+    if (flirtStatus == false) {
       this.makeUnhappy();
     } else {
       this.makeHappy();

object-pool/src/main/java/com/iluwatar/object/pool/Oliphaunt.java

@@ -22,8 +22,6 @@
  */
 package com.iluwatar.object.pool;
 
-import java.util.concurrent.atomic.AtomicInteger;
-
 /**
  * 
  * Oliphaunts are expensive to create
@@ -31,7 +29,7 @@ import java.util.concurrent.atomic.AtomicInteger;
  */
 public class Oliphaunt {
 
-  private static AtomicInteger counter = new AtomicInteger(0);
+  private static int counter = 1;
 
   private final int id;
 
@@ -39,7 +37,7 @@ public class Oliphaunt {
    * Constructor
    */
   public Oliphaunt() {
-    id = counter.incrementAndGet();
+    id = counter++;
     try {
       Thread.sleep(1000);
     } catch (InterruptedException e) {

object-pool/src/test/java/com/iluwatar/object/pool/OliphauntPoolTest.java

@@ -49,23 +49,23 @@ public class OliphauntPoolTest {
   public void testSubsequentCheckinCheckout() {
     assertTimeout(ofMillis(5000), () -> {
       final OliphauntPool pool = new OliphauntPool();
-      assertEquals("Pool available=0 inUse=0", pool.toString());
+      assertEquals(pool.toString(), "Pool available=0 inUse=0");
 
       final Oliphaunt expectedOliphaunt = pool.checkOut();
-      assertEquals("Pool available=0 inUse=1", pool.toString());
+      assertEquals(pool.toString(), "Pool available=0 inUse=1");
 
       pool.checkIn(expectedOliphaunt);
-      assertEquals("Pool available=1 inUse=0", pool.toString());
+      assertEquals(pool.toString(), "Pool available=1 inUse=0");
 
       for (int i = 0; i < 100; i++) {
         final Oliphaunt oliphaunt = pool.checkOut();
-        assertEquals("Pool available=0 inUse=1", pool.toString());
+        assertEquals(pool.toString(), "Pool available=0 inUse=1");
         assertSame(expectedOliphaunt, oliphaunt);
         assertEquals(expectedOliphaunt.getId(), oliphaunt.getId());
         assertEquals(expectedOliphaunt.toString(), oliphaunt.toString());
 
         pool.checkIn(oliphaunt);
-        assertEquals("Pool available=1 inUse=0", pool.toString());
+        assertEquals(pool.toString(), "Pool available=1 inUse=0");
       }
     });
   }

observer/src/test/java/com/iluwatar/observer/generic/ObserverTest.java

@@ -42,7 +42,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  * @author Jeroen Meulemeester
  */
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
-public abstract class ObserverTest<O extends Observer<?, ?, WeatherType>> {
+public abstract class ObserverTest<O extends Observer> {
 
   private InMemoryAppender appender;
 

poison-pill/src/test/java/com/iluwatar/poison/pill/PoisonMessageTest.java

@@ -36,34 +36,38 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 public class PoisonMessageTest {
 
   @Test
-  public void testAddHeader() {
+  public void testAddHeader() throws Exception {
     assertThrows(UnsupportedOperationException.class, () -> {
       POISON_PILL.addHeader(Headers.SENDER, "sender");
     });
   }
 
   @Test
-  public void testGetHeader() {
+  public void testGetHeader() throws Exception {
     assertThrows(UnsupportedOperationException.class, () -> {
       POISON_PILL.getHeader(Headers.SENDER);
     });
   }
 
   @Test
-  public void testGetHeaders() {
-    assertThrows(UnsupportedOperationException.class, POISON_PILL::getHeaders);
+  public void testGetHeaders() throws Exception {
+    assertThrows(UnsupportedOperationException.class, () -> {
+      POISON_PILL.getHeaders();
+    });
   }
 
   @Test
-  public void testSetBody() {
+  public void testSetBody() throws Exception {
     assertThrows(UnsupportedOperationException.class, () -> {
       POISON_PILL.setBody("Test message.");
     });
   }
 
   @Test
-  public void testGetBody() {
-    assertThrows(UnsupportedOperationException.class, POISON_PILL::getBody);
+  public void testGetBody() throws Exception {
+    assertThrows(UnsupportedOperationException.class, () -> {
+      POISON_PILL.getBody();
+    });
   }
 
 }

producer-consumer/src/test/java/com/iluwatar/producer/consumer/ProducerTest.java

@@ -39,7 +39,7 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
 public class ProducerTest {
 
   @Test
-  public void testProduce() {
+  public void testProduce() throws Exception {
     assertTimeout(ofMillis(6000), () -> {
       final ItemQueue queue = mock(ItemQueue.class);
       final Producer producer = new Producer("producer", queue);

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

@@ -155,15 +155,19 @@ public class App {
    * This is an async method and does not wait until the file is downloaded.
    */
   private Promise<String> download(String urlString) {
-    return new Promise<String>()
+    Promise<String> downloadPromise = new Promise<String>()
         .fulfillInAsync(
-            () -> Utility.downloadFile(urlString), executor)
+            () -> {
+              return Utility.downloadFile(urlString);
+            }, executor)
         .onError(
             throwable -> {
               throwable.printStackTrace();
               taskCompleted();
             }
         );
+
+    return downloadPromise;
   }
 
   private void stop() throws InterruptedException {

promise/src/main/java/com/iluwatar/promise/Utility.java

@@ -32,6 +32,7 @@ import java.io.FileWriter;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.net.MalformedURLException;
 import java.net.URL;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -110,7 +111,7 @@ public class Utility {
    * Downloads the contents from the given urlString, and stores it in a temporary directory.
    * @return the absolute path of the file downloaded.
    */
-  public static String downloadFile(String urlString) throws IOException {
+  public static String downloadFile(String urlString) throws MalformedURLException, IOException {
     LOGGER.info("Downloading contents from url: {}", urlString);
     URL url = new URL(urlString);
     File file = File.createTempFile("promise_pattern", null);

promise/src/test/java/com/iluwatar/promise/PromiseTest.java

@@ -76,8 +76,12 @@ public class PromiseTest {
   private void testWaitingForeverForPromiseToBeFulfilled() 
       throws InterruptedException, TimeoutException {
     Promise<Integer> promise = new Promise<>();
-    promise.fulfillInAsync(() -> {
-      throw new RuntimeException("Barf!");
+    promise.fulfillInAsync(new Callable<Integer>() {
+
+      @Override
+      public Integer call() throws Exception {
+        throw new RuntimeException("Barf!");
+      }
     }, executor);
     
     try {
@@ -100,8 +104,12 @@ public class PromiseTest {
   private void testWaitingSomeTimeForPromiseToBeFulfilled() 
       throws InterruptedException, TimeoutException {
     Promise<Integer> promise = new Promise<>();
-    promise.fulfillInAsync(() -> {
-      throw new RuntimeException("Barf!");
+    promise.fulfillInAsync(new Callable<Integer>() {
+
+      @Override
+      public Integer call() throws Exception {
+        throw new RuntimeException("Barf!");
+      }
     }, executor);
     
     try {
@@ -142,8 +150,12 @@ public class PromiseTest {
       throws InterruptedException, ExecutionException, TimeoutException {
     Promise<Void> dependentPromise = promise
         .fulfillInAsync(new NumberCrunchingTask(), executor)
-        .thenAccept(value -> {
-          throw new RuntimeException("Barf!");
+        .thenAccept(new Consumer<Integer>() {
+
+          @Override
+          public void accept(Integer value) {
+            throw new RuntimeException("Barf!");
+          }
         });
 
     try {
@@ -186,8 +198,12 @@ public class PromiseTest {
       throws InterruptedException, ExecutionException, TimeoutException {
     Promise<String> dependentPromise = promise
         .fulfillInAsync(new NumberCrunchingTask(), executor)
-        .thenApply(value -> {
-          throw new RuntimeException("Barf!");
+        .thenApply(new Function<Integer, String>() {
+
+          @Override
+          public String apply(Integer value) {
+            throw new RuntimeException("Barf!");
+          }
         });
 
     try {

property/src/test/java/com/iluwatar/property/CharacterTest.java

@@ -73,7 +73,7 @@ public class CharacterTest {
   }
 
   @Test
-  public void testToString() {
+  public void testToString() throws Exception {
     final Character prototype = new Character();
     prototype.set(Stats.ARMOR, 1);
     prototype.set(Stats.AGILITY, 2);
@@ -91,7 +91,7 @@ public class CharacterTest {
   }
 
   @Test
-  public void testName() {
+  public void testName() throws Exception {
     final Character prototype = new Character();
     prototype.set(Stats.ARMOR, 1);
     prototype.set(Stats.INTELLECT, 2);
@@ -107,7 +107,7 @@ public class CharacterTest {
   }
 
   @Test
-  public void testType() {
+  public void testType() throws Exception {
     final Character prototype = new Character();
     prototype.set(Stats.ARMOR, 1);
     prototype.set(Stats.INTELLECT, 2);

prototype/src/main/java/com/iluwatar/prototype/ElfBeast.java

@@ -40,7 +40,7 @@ public class ElfBeast extends Beast {
   }
 
   @Override
-  public Beast copy() {
+  public Beast copy() throws CloneNotSupportedException {
     return new ElfBeast(this);
   }
 

prototype/src/main/java/com/iluwatar/prototype/ElfMage.java

@@ -41,7 +41,7 @@ public class ElfMage extends Mage {
   }
 
   @Override
-  public ElfMage copy() {
+  public ElfMage copy() throws CloneNotSupportedException {
     return new ElfMage(this);
   }
 

prototype/src/main/java/com/iluwatar/prototype/ElfWarlord.java

@@ -40,7 +40,7 @@ public class ElfWarlord extends Warlord {
   }
 
   @Override
-  public ElfWarlord copy() {
+  public ElfWarlord copy() throws CloneNotSupportedException {
     return new ElfWarlord(this);
   }
 

prototype/src/main/java/com/iluwatar/prototype/OrcBeast.java

@@ -40,7 +40,7 @@ public class OrcBeast extends Beast {
   }
 
   @Override
-  public Beast copy() {
+  public Beast copy() throws CloneNotSupportedException {
     return new OrcBeast(this);
   }
 

prototype/src/main/java/com/iluwatar/prototype/OrcMage.java

@@ -40,7 +40,7 @@ public class OrcMage extends Mage {
   }
 
   @Override
-  public OrcMage copy() {
+  public OrcMage copy() throws CloneNotSupportedException {
     return new OrcMage(this);
   }
 

prototype/src/main/java/com/iluwatar/prototype/OrcWarlord.java

@@ -40,7 +40,7 @@ public class OrcWarlord extends Warlord {
   }
 
   @Override
-  public OrcWarlord copy() {
+  public OrcWarlord copy() throws CloneNotSupportedException {
     return new OrcWarlord(this);
   }
 

queue-load-leveling/src/main/java/com/iluwatar/queue/load/leveling/App.java

@@ -110,6 +110,8 @@ public class App {
         LOGGER.info("Executor was shut down and Exiting.");
         executor.shutdownNow();
       }
+    } catch (InterruptedException ie) {
+      LOGGER.error(ie.getMessage());
     } catch (Exception e) {
       LOGGER.error(e.getMessage());
     }

queue-load-leveling/src/main/java/com/iluwatar/queue/load/leveling/ServiceExecutor.java

@@ -58,6 +58,8 @@ public class ServiceExecutor implements Runnable {
 
         Thread.sleep(1000);
       }
+    } catch (InterruptedException ie) {
+      LOGGER.error(ie.getMessage());
     } catch (Exception e) {
       LOGGER.error(e.getMessage());
     }

queue-load-leveling/src/main/java/com/iluwatar/queue/load/leveling/TaskGenerator.java

@@ -80,6 +80,8 @@ public class TaskGenerator implements Task, Runnable {
         // Make the current thread to sleep after every Message submission.
         Thread.sleep(1000);
       }
+    } catch (InterruptedException ie) {
+      LOGGER.error(ie.getMessage());
     } catch (Exception e) {
       LOGGER.error(e.getMessage());
     }

queue-load-leveling/src/test/java/com/iluwatar/queue/load/leveling/MessageQueueTest.java

@@ -42,7 +42,7 @@ public class MessageQueueTest {
     msgQueue.submitMsg(new Message("MessageQueue Test"));
     
     // retrieve message
-    assertEquals("MessageQueue Test", msgQueue.retrieveMsg().getMsg());
+    assertEquals(msgQueue.retrieveMsg().getMsg(), "MessageQueue Test");
   }
 
 }

queue-load-leveling/src/test/java/com/iluwatar/queue/load/leveling/MessageTest.java

@@ -39,6 +39,6 @@ public class MessageTest {
     // Parameterized constructor test.
     String testMsg = "Message Test";
     Message msg = new Message(testMsg);
-    assertEquals(testMsg, msg.getMsg());
+    assertEquals(msg.getMsg(), testMsg);
   }
 }

repository/src/test/java/com/iluwatar/repository/AppConfigTest.java

@@ -22,6 +22,14 @@
  */
 package com.iluwatar.repository;
 
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+import javax.sql.DataSource;
+
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -30,13 +38,6 @@ import org.springframework.test.context.junit.jupiter.SpringExtension;
 import org.springframework.test.context.support.AnnotationConfigContextLoader;
 import org.springframework.transaction.annotation.Transactional;
 
-import javax.sql.DataSource;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-
 /**
  * This case is Just for test the Annotation Based configuration
  * 
@@ -69,7 +70,7 @@ public class AppConfigTest {
       result = resultSet.getString(1);
 
     }
-    assertEquals(expected, result);
+    assertTrue(result.equals(expected));
   }
 
 }

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

@@ -31,7 +31,7 @@ import java.io.IOException;
  */
 public class AppTest {
   @Test
-  public void test() {
+  public void test() throws IOException {
     String[] args = {};
     App.main(args);
   }

repository/src/test/java/com/iluwatar/repository/RepositoryTest.java

@@ -109,7 +109,9 @@ public class RepositoryTest {
     List<Person> persons = repository.findAll(new PersonSpecifications.AgeBetweenSpec(20, 40));
 
     assertEquals(3, persons.size());
-    assertTrue(persons.stream().allMatch(item -> item.getAge() > 20 && item.getAge() < 40));
+    assertTrue(persons.stream().allMatch((item) -> {
+      return item.getAge() > 20 && item.getAge() < 40;
+    }));
   }
 
   @Test

retry/src/test/java/com/iluwatar/retry/FindCustomerTest.java

@@ -53,7 +53,7 @@ public class FindCustomerTest {
    * @throws Exception the expected exception
    */
   @Test
-  public void oneException() {
+  public void oneException() throws Exception {
     assertThrows(BusinessException.class, () -> {
       new FindCustomer("123", new BusinessException("test")).perform();
     });

retry/src/test/java/com/iluwatar/retry/RetryTest.java

@@ -40,7 +40,7 @@ public class RetryTest {
    * Should contain all errors thrown.
    */
   @Test
-  public void errors() {
+  public void errors() throws Exception {
     final BusinessException e = new BusinessException("unhandled");
     final Retry<String> retry = new Retry<>(
         () -> { throw e; },

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

@@ -31,7 +31,7 @@ import java.io.IOException;
  */
 public class AppTest {
   @Test
-  public void test() {
+  public void test() throws IOException {
     String[] args = {};
     App.main(args);
   }

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

@@ -37,16 +37,16 @@ public class FruitBowlTest {
   public void fruitBowlTest() {
     FruitBowl fbowl = new FruitBowl();
     
-    assertEquals(0, fbowl.countFruit());
+    assertEquals(fbowl.countFruit(), 0);
     
     for (int i = 1; i <= 10; i++) {
       fbowl.put(new Fruit(Fruit.FruitType.LEMON));
-      assertEquals(i, fbowl.countFruit());
+      assertEquals(fbowl.countFruit(), i);
     }
 
     for (int i = 9; i >= 0; i--) {
       assertNotNull(fbowl.take());
-      assertEquals(i, fbowl.countFruit());
+      assertEquals(fbowl.countFruit(), i);
     }
 
     assertNull(fbowl.take());

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

@@ -36,12 +36,12 @@ public class SemaphoreTest {
   public void acquireReleaseTest() {
     Semaphore sphore = new Semaphore(3);
 
-    assertEquals(3, sphore.getAvailableLicenses());
+    assertEquals(sphore.getAvailableLicenses(), 3);
 
     for (int i = 2; i >= 0; i--) {
       try {
         sphore.acquire();
-        assertEquals(i, sphore.getAvailableLicenses());
+        assertEquals(sphore.getAvailableLicenses(), i);
       } catch (InterruptedException e) {
         fail(e.toString());
       }
@@ -49,10 +49,10 @@ public class SemaphoreTest {
   
     for (int i = 1; i <= 3; i++) {
       sphore.release();
-      assertEquals(i, sphore.getAvailableLicenses());
+      assertEquals(sphore.getAvailableLicenses(), i);
     }
 
     sphore.release();
-    assertEquals(3, sphore.getAvailableLicenses());
+    assertEquals(sphore.getAvailableLicenses(), 3);
   }
 }

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

@@ -36,7 +36,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 public class QueenTest {
 
   @Test
-  public void testNotFlirtyUncomplemented() {
+  public void testNotFlirtyUncomplemented() throws Exception {
     final Queen queen = new Queen();
     queen.setFlirtiness(false);
     queen.changeMood();
@@ -44,7 +44,7 @@ public class QueenTest {
   }
   
   @Test
-  public void testNotFlirtyComplemented() {
+  public void testNotFlirtyComplemented() throws Exception {
     final Queen queen = new Queen();
     queen.setFlirtiness(false);
     queen.receiveCompliments();
@@ -53,14 +53,14 @@ public class QueenTest {
   }
   
   @Test
-  public void testFlirtyUncomplemented() {
+  public void testFlirtyUncomplemented() throws Exception {
     final Queen queen = new Queen();
     queen.changeMood();
     assertFalse(queen.getMood());
   }
   
   @Test
-  public void testFlirtyComplemented() {
+  public void testFlirtyComplemented() throws Exception {
     final Queen queen = new Queen();
     queen.receiveCompliments();
     queen.changeMood();

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

@@ -41,7 +41,7 @@ import static org.mockito.Mockito.when;
 public class ServantTest {
 
   @Test
-  public void testFeed() {
+  public void testFeed() throws Exception {
     final Royalty royalty = mock(Royalty.class);
     final Servant servant = new Servant("test");
     servant.feed(royalty);
@@ -50,7 +50,7 @@ public class ServantTest {
   }
 
   @Test
-  public void testGiveWine() {
+  public void testGiveWine() throws Exception {
     final Royalty royalty = mock(Royalty.class);
     final Servant servant = new Servant("test");
     servant.giveWine(royalty);
@@ -59,7 +59,7 @@ public class ServantTest {
   }
 
   @Test
-  public void testGiveCompliments() {
+  public void testGiveCompliments() throws Exception {
     final Royalty royalty = mock(Royalty.class);
     final Servant servant = new Servant("test");
     servant.giveCompliments(royalty);
@@ -68,7 +68,7 @@ public class ServantTest {
   }
 
   @Test
-  public void testCheckIfYouWillBeHanged() {
+  public void testCheckIfYouWillBeHanged() throws Exception {
     final Royalty goodMoodRoyalty = mock(Royalty.class);
     when(goodMoodRoyalty.getMood()).thenReturn(true);
 

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

@@ -33,7 +33,7 @@ import org.apache.log4j.Logger;
  * find person from persons collection
  * Created by dheeraj.mummar on 3/5/18.
  */
-public class FindPersonApiHandler extends AbstractDynamoDbHandler<Person>
+public class FindPersonApiHandler extends AbstractDynamoDbHandler
     implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
 
   private static final Logger LOG = Logger.getLogger(FindPersonApiHandler.class);

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

@@ -35,7 +35,7 @@ import java.io.IOException;
  * save person into persons collection
  * Created by dheeraj.mummar on 3/4/18.
  */
-public class SavePersonApiHandler extends AbstractDynamoDbHandler<Person>
+public class SavePersonApiHandler extends AbstractDynamoDbHandler
     implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
 
   private static final Logger LOG = Logger.getLogger(SavePersonApiHandler.class);

service-layer/bin/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2014-2016 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.iluwatar</groupId>
+    <artifactId>java-design-patterns</artifactId>
+    <version>1.0-SNAPSHOT</version>
+  </parent>
+  <artifactId>dao</artifactId>
+  <dependencies>
+	<dependency>
+	    <groupId>org.hibernate</groupId>
+	    <artifactId>hibernate-core</artifactId>
+	</dependency>
+	<dependency>
+		<groupId>com.h2database</groupId>
+		<artifactId>h2</artifactId>
+	</dependency>  
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>