Set version for milestone 1.11.0

Solves #404 Refactor dao

LICENSE.md

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2014 Ilkka Seppälä
+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

abstract-factory/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>abstract-factory</artifactId>
   <dependencies>

abstract-factory/src/main/java/com/iluwatar/abstractfactory/App.java

@@ -52,14 +52,6 @@ public class App {
     setArmy(factory.createArmy());
   }
 
-  ElfKingdomFactory getElfKingdomFactory() {
-    return new ElfKingdomFactory();
-  }
-
-  OrcKingdomFactory getOrcKingdomFactory() {
-    return new OrcKingdomFactory();
-  }
-
   King getKing(final KingdomFactory factory) {
     return factory.createKing();
   }
@@ -107,17 +99,13 @@ public class App {
     App app = new App();
 
     System.out.println("Elf Kingdom");
-    KingdomFactory elfKingdomFactory;
-    elfKingdomFactory = app.getElfKingdomFactory();
-    app.createKingdom(elfKingdomFactory);
+    app.createKingdom(new ElfKingdomFactory());
     System.out.println(app.getArmy().getDescription());
     System.out.println(app.getCastle().getDescription());
     System.out.println(app.getKing().getDescription());
 
     System.out.println("\nOrc Kingdom");
-    KingdomFactory orcKingdomFactory;
-    orcKingdomFactory = app.getOrcKingdomFactory();
-    app.createKingdom(orcKingdomFactory);
+    app.createKingdom(new OrcKingdomFactory());
     System.out.println(app.getArmy().getDescription());
     System.out.println(app.getCastle().getDescription());
     System.out.println(app.getKing().getDescription());

abstract-factory/src/test/java/com/iluwatar/abstractfactory/AbstractFactoryTest.java

@@ -36,8 +36,8 @@ public class AbstractFactoryTest {
 
   @Before
   public void setUp() {
-    elfFactory = app.getElfKingdomFactory();
-    orcFactory = app.getOrcKingdomFactory();
+    elfFactory = new ElfKingdomFactory();
+    orcFactory = new OrcKingdomFactory();
   }
 
   @Test

adapter/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>adapter</artifactId>
   <dependencies>

async-method-invocation/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>async-method-invocation</artifactId>
   <dependencies>

bridge/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>bridge</artifactId>
   <dependencies>

builder/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>builder</artifactId>
   <dependencies>

builder/src/main/java/com/iluwatar/builder/Hero.java

@@ -27,7 +27,7 @@ package com.iluwatar.builder;
  * Hero, the class with many parameters.
  * 
  */
-public class Hero {
+public final class Hero {
 
   private final Profession profession;
   private final String name;
@@ -36,6 +36,15 @@ public class Hero {
   private final Armor armor;
   private final Weapon weapon;
 
+  private Hero(HeroBuilder builder) {
+    this.profession = builder.profession;
+    this.name = builder.name;
+    this.hairColor = builder.hairColor;
+    this.hairType = builder.hairType;
+    this.weapon = builder.weapon;
+    this.armor = builder.armor;
+  }
+
   public Profession getProfession() {
     return profession;
   }
@@ -88,15 +97,6 @@ public class Hero {
     return sb.toString();
   }
 
-  private Hero(HeroBuilder builder) {
-    this.profession = builder.profession;
-    this.name = builder.name;
-    this.hairColor = builder.hairColor;
-    this.hairType = builder.hairType;
-    this.weapon = builder.weapon;
-    this.armor = builder.armor;
-  }
-
   /**
    * 
    * The builder class.

business-delegate/pom.xml

@@ -30,7 +30,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.10.0</version>
+		<version>1.11.0</version>
 	</parent>
 	<artifactId>business-delegate</artifactId>
 	<dependencies>

caching/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>caching</artifactId>
   <dependencies>

caching/src/main/java/com/iluwatar/caching/AppManager.java

@@ -33,7 +33,7 @@ import java.text.ParseException;
  * CacheStore class.
  *
  */
-public class AppManager {
+public final class AppManager {
 
   private static CachingPolicy cachingPolicy;
 

caching/src/main/java/com/iluwatar/caching/CacheStore.java

@@ -22,7 +22,7 @@
  */
 package com.iluwatar.caching;
 
-import java.util.ArrayList;
+import java.util.List;
 
 /**
  *
@@ -31,7 +31,7 @@ import java.util.ArrayList;
  */
 public class CacheStore {
 
-  static LruCache cache = null;
+  static LruCache cache;
 
   private CacheStore() {
   }
@@ -134,7 +134,7 @@ public class CacheStore {
     if (null == cache) {
       return;
     }
-    ArrayList<UserAccount> listOfUserAccounts = cache.getCacheDataInListForm();
+    List<UserAccount> listOfUserAccounts = cache.getCacheDataInListForm();
     for (UserAccount userAccount : listOfUserAccounts) {
       DbManager.upsertDb(userAccount);
     }
@@ -144,7 +144,7 @@ public class CacheStore {
    * Print user accounts
    */
   public static String print() {
-    ArrayList<UserAccount> listOfUserAccounts = cache.getCacheDataInListForm();
+    List<UserAccount> listOfUserAccounts = cache.getCacheDataInListForm();
     StringBuilder sb = new StringBuilder();
     sb.append("\n--CACHE CONTENT--\n");
     for (UserAccount userAccount : listOfUserAccounts) {

caching/src/main/java/com/iluwatar/caching/DbManager.java

@@ -24,6 +24,7 @@ package com.iluwatar.caching;
 
 import java.text.ParseException;
 import java.util.HashMap;
+import java.util.Map;
 
 import org.bson.Document;
 
@@ -43,13 +44,13 @@ import com.mongodb.client.model.UpdateOptions;
  * during runtime (createVirtualDB()).</p>
  * 
  */
-public class DbManager {
+public final class DbManager {
 
   private static MongoClient mongoClient;
   private static MongoDatabase db;
   private static boolean useMongoDB;
 
-  private static HashMap<String, UserAccount> virtualDB;
+  private static Map<String, UserAccount> virtualDB;
 
   private DbManager() {
   }

caching/src/main/java/com/iluwatar/caching/LruCache.java

@@ -24,6 +24,8 @@ package com.iluwatar.caching;
 
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
 /**
  *
@@ -49,9 +51,9 @@ public class LruCache {
   }
 
   int capacity;
-  HashMap<String, Node> cache = new HashMap<>();
-  Node head = null;
-  Node end = null;
+  Map<String, Node> cache = new HashMap<>();
+  Node head;
+  Node end;
 
   public LruCache(int capacity) {
     this.capacity = capacity;
@@ -161,7 +163,7 @@ public class LruCache {
    *
    * Returns cache data in list form.
    */
-  public ArrayList<UserAccount> getCacheDataInListForm() {
+  public List<UserAccount> getCacheDataInListForm() {
     ArrayList<UserAccount> listOfCacheData = new ArrayList<>();
     Node temp = head;
     while (temp != null) {

callback/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>callback</artifactId>
   <dependencies>

chain/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>chain</artifactId>
   <dependencies>

chain/src/main/java/com/iluwatar/chain/Request.java

@@ -44,7 +44,7 @@ public class Request {
    * Indicates if the request is handled or not. A request can only switch state from unhandled to
    * handled, there's no way to 'unhandle' a request
    */
-  private boolean handled = false;
+  private boolean handled;
 
   /**
    * Create a new request of the given type and accompanied description.

command/README.md

@@ -38,6 +38,7 @@ Use the Command pattern when you want to
 ## Real world examples
 
 * [java.lang.Runnable](http://docs.oracle.com/javase/8/docs/api/java/lang/Runnable.html)
+* [Netflix Hystrix](https://github.com/Netflix/Hystrix/wiki)
 
 ## Credits
 

command/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>command</artifactId>
   <dependencies>

composite/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>composite</artifactId>
   <dependencies>

dao/etc/dao.ucls

@@ -1,45 +1,71 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <class-diagram version="1.1.8" icons="true" always-add-relationships="false" generalizations="true" realizations="true" 
   associations="true" dependencies="false" nesting-relationships="true">  
-  <class id="1" language="java" name="com.iluwatar.Customer" project="dao" 
-    file="/dao/src/main/java/com/iluwatar/Customer.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="176" y="337"/>    
+  <class id="1" language="java" name="com.iluwatar.dao.App" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/App.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="910" y="191"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+      <attributes public="true" package="true" protected="true" private="false" static="true"/>      
+      <operations public="true" package="true" protected="true" private="false" static="true"/>    
     </display>  
   </class>  
-  <class id="2" language="java" name="com.iluwatar.CustomerDaoImpl" project="dao" 
-    file="/dao/src/main/java/com/iluwatar/CustomerDaoImpl.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="540" y="334"/>    
-    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
-      sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
-    </display>  
-  </class>  
-  <interface id="3" language="java" name="com.iluwatar.CustomerDao" project="dao" 
-    file="/dao/src/main/java/com/iluwatar/CustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="536" y="131"/>    
+  <interface id="2" language="java" name="com.iluwatar.dao.CustomerDao" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/CustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="536" y="187"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </interface>  
-  <realization id="4">    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="3"/>  
-  </realization>  
-  <association id="5">    
-    <end type="SOURCE" refId="2" navigable="false">      
-      <attribute id="6" name="customers"/>      
-      <multiplicity id="7" minimum="0" maximum="2147483647"/>    
+  <class id="3" language="java" name="com.iluwatar.dao.InMemoryCustomerDao" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/InMemoryCustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="289" y="455"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="false" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="4" language="java" name="com.iluwatar.dao.DBCustomerDao" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/DBCustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="751" y="456"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="false" static="true"/>      
+      <operations public="true" package="true" protected="true" private="false" static="true"/>    
+    </display>  
+  </class>  
+  <interface id="5" language="java" name="javax.sql.DataSource" project="dao" 
+    file="/opt/Softwares/Eclipses/MARS/eclipse/jre/lib/rt.jar" binary="true" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="1083" y="459"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </interface>  
+  <association id="6">    
+    <end type="SOURCE" refId="4" navigable="false">      
+      <attribute id="7" name="dataSource"/>      
+      <multiplicity id="8" minimum="0" maximum="1"/>    
     </end>    
-    <end type="TARGET" refId="1" navigable="true"/>    
+    <end type="TARGET" refId="5" navigable="true"/>    
     <display labels="true" multiplicity="true"/>  
   </association>  
+  <realization id="9">    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="2"/>  
+  </realization>  
+  <dependency id="10">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="2"/>  
+  </dependency>  
+  <realization id="11">    
+    <end type="SOURCE" refId="4"/>    
+    <end type="TARGET" refId="2"/>  
+  </realization>  
   <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
     sort-features="false" accessors="true" visibility="true">    
     <attributes public="true" package="true" protected="true" private="true" static="true"/>    

dao/pom.xml

@@ -30,7 +30,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>dao</artifactId>
 
@@ -44,6 +44,18 @@
       <groupId>log4j</groupId>
       <artifactId>log4j</artifactId>
     </dependency>
+    <dependency>
+        <groupId>com.h2database</groupId>
+        <artifactId>h2</artifactId>
+      </dependency>
+    <dependency>
+      <groupId>de.bechte.junit</groupId>
+      <artifactId>junit-hierarchicalcontextrunner</artifactId>
+    </dependency>
+    <dependency>
+        <groupId>org.mockito</groupId>
+        <artifactId>mockito-core</artifactId>
+    </dependency>
   </dependencies>
 
   <build>

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

@@ -20,49 +20,101 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Stream;
+
+import javax.sql.DataSource;
 
 import org.apache.log4j.Logger;
+import org.h2.jdbcx.JdbcDataSource;
 
 /**
- * 
  * Data Access Object (DAO) is an object that provides an abstract interface to some type of
  * database or other persistence mechanism. By mapping application calls to the persistence layer,
  * DAO provide some specific data operations without exposing details of the database. This
  * isolation supports the Single responsibility principle. It separates what data accesses the
  * application needs, in terms of domain-specific objects and data types (the public interface of
  * the DAO), from how these needs can be satisfied with a specific DBMS.
- * <p>
- * With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without
- * directly interacting with the data. The below example demonstrates basic CRUD operations: select,
- * add, update, and delete.
+ *
+ * <p>With the DAO pattern, we can use various method calls to retrieve/add/delete/update data 
+ * without directly interacting with the data source. The below example demonstrates basic CRUD 
+ * operations: select, add, update, and delete.
+ * 
  * 
  */
 public class App {
-
+  private static final String DB_URL = "jdbc:h2:~/dao:customerdb";
   private static Logger log = Logger.getLogger(App.class);
-
+  
   /**
    * Program entry point.
    * 
    * @param args command line args.
+   * @throws Exception if any error occurs. 
    */
-  public static void main(final String[] args) {
-    final CustomerDaoImpl customerDao = new CustomerDaoImpl(generateSampleCustomers());
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
-    log.info("customerDao.getCusterById(2): " + customerDao.getCustomerById(2));
+  public static void main(final String[] args) throws Exception {
+    final CustomerDao inMemoryDao = new InMemoryCustomerDao();
+    performOperationsUsing(inMemoryDao);
+    
+    final DataSource dataSource = createDataSource();
+    createSchema(dataSource);
+    final CustomerDao dbDao = new DbCustomerDao(dataSource);
+    performOperationsUsing(dbDao);
+    deleteSchema(dataSource);
+  }
+
+  private static void deleteSchema(DataSource dataSource) throws SQLException {
+    try (Connection connection = dataSource.getConnection();
+        Statement statement = connection.createStatement()) {
+      statement.execute(CustomerSchemaSql.DELETE_SCHEMA_SQL);
+    }
+  }
+
+  private static void createSchema(DataSource dataSource) throws SQLException {
+    try (Connection connection = dataSource.getConnection();
+        Statement statement = connection.createStatement()) {
+      statement.execute(CustomerSchemaSql.CREATE_SCHEMA_SQL);
+    }
+  }
+
+  private static DataSource createDataSource() {
+    JdbcDataSource dataSource = new JdbcDataSource();
+    dataSource.setURL(DB_URL);
+    return dataSource;
+  }
+
+  private static void performOperationsUsing(final CustomerDao customerDao) throws Exception {
+    addCustomers(customerDao);
+    log.info("customerDao.getAllCustomers(): ");
+    try (Stream<Customer> customerStream = customerDao.getAll()) {
+      customerStream.forEach((customer) -> log.info(customer));
+    }
+    log.info("customerDao.getCustomerById(2): " + customerDao.getById(2));
     final Customer customer = new Customer(4, "Dan", "Danson");
-    customerDao.addCustomer(customer);
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
+    customerDao.add(customer);
+    log.info("customerDao.getAllCustomers(): " + customerDao.getAll());
     customer.setFirstName("Daniel");
     customer.setLastName("Danielson");
-    customerDao.updateCustomer(customer);
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
-    customerDao.deleteCustomer(customer);
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
+    customerDao.update(customer);
+    log.info("customerDao.getAllCustomers(): ");
+    try (Stream<Customer> customerStream = customerDao.getAll()) {
+      customerStream.forEach((cust) -> log.info(cust));
+    }
+    customerDao.delete(customer);
+    log.info("customerDao.getAllCustomers(): " + customerDao.getAll());
+  }
+
+  private static void addCustomers(CustomerDao customerDao) throws Exception {
+    for (Customer customer : generateSampleCustomers()) {
+      customerDao.add(customer);
+    }
   }
 
   /**

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

@@ -20,11 +20,11 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
 /**
- * 
- * Customer
+ * A customer POJO that represents the data that will be read from the data source.
  *
  */
 public class Customer {
@@ -34,7 +34,7 @@ public class Customer {
   private String lastName;
 
   /**
-   * Constructor
+   * Creates an instance of customer.
    */
   public Customer(final int id, final String firstName, final String lastName) {
     this.id = id;
@@ -73,12 +73,12 @@ public class Customer {
   }
 
   @Override
-  public boolean equals(final Object o) {
+  public boolean equals(final Object that) {
     boolean isEqual = false;
-    if (this == o) {
+    if (this == that) {
       isEqual = true;
-    } else if (o != null && getClass() == o.getClass()) {
-      final Customer customer = (Customer) o;
+    } else if (that != null && getClass() == that.getClass()) {
+      final Customer customer = (Customer) that;
       if (getId() == customer.getId()) {
         isEqual = true;
       }

dao/src/main/java/com/iluwatar/dao/CustomerDao.java

@@ -20,24 +20,62 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
-import java.util.List;
+import java.util.Optional;
+import java.util.stream.Stream;
 
 /**
+ * In an application the Data Access Object (DAO) is a part of Data access layer. It is an object
+ * that provides an interface to some type of persistence mechanism. By mapping application calls
+ * to the persistence layer, DAO provides some specific data operations without exposing details 
+ * of the database. This isolation supports the Single responsibility principle. It separates what
+ * data accesses the application needs, in terms of domain-specific objects and data types 
+ * (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS,
+ * database schema, etc.
  * 
- * CustomerDao
- *
+ * <p>Any change in the way data is stored and retrieved will not change the client code as the 
+ * client will be using interface and need not worry about exact source.
+ * 
+ * @see InMemoryCustomerDao
+ * @see DbCustomerDao
  */
 public interface CustomerDao {
 
-  List<Customer> getAllCustomers();
+  /**
+   * @return all the customers as a stream. The stream may be lazily or eagerly evaluated based 
+   *     on the implementation. The stream must be closed after use.
+   * @throws Exception if any error occurs.
+   */
+  Stream<Customer> getAll() throws Exception;
+  
+  /**
+   * @param id unique identifier of the customer.
+   * @return an optional with customer if a customer with unique identifier <code>id</code>
+   *     exists, empty optional otherwise.
+   * @throws Exception if any error occurs.
+   */
+  Optional<Customer> getById(int id) throws Exception;
 
-  Customer getCustomerById(int id);
+  /**
+   * @param customer the customer to be added.
+   * @return true if customer is successfully added, false if customer already exists.
+   * @throws Exception if any error occurs.
+   */
+  boolean add(Customer customer) throws Exception;
 
-  void addCustomer(Customer customer);
+  /**
+   * @param customer the customer to be updated.
+   * @return true if customer exists and is successfully updated, false otherwise.
+   * @throws Exception if any error occurs.
+   */
+  boolean update(Customer customer) throws Exception;
 
-  void updateCustomer(Customer customer);
-
-  void deleteCustomer(Customer customer);
+  /**
+   * @param customer the customer to be deleted.
+   * @return true if customer exists and is successfully deleted, false otherwise.
+   * @throws Exception if any error occurs.
+   */
+  boolean delete(Customer customer) throws Exception;
 }

dao/src/main/java/com/iluwatar/dao/CustomerDaoImpl.java

@@ -1,84 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014 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.
- */
-package com.iluwatar.dao;
-
-import java.util.List;
-
-/**
- * 
- * The data access object (DAO) is an object that provides an abstract interface to some type of
- * database or other persistence mechanism. By mapping application calls to the persistence layer,
- * DAO provide some specific data operations without exposing details of the database. This
- * isolation supports the Single responsibility principle. It separates what data accesses the
- * application needs, in terms of domain-specific objects and data types (the public interface of
- * the DAO), from how these needs can be satisfied with a specific DBMS, database schema, etc.
- * 
- */
-public class CustomerDaoImpl implements CustomerDao {
-
-  // Represents the DB structure for our example so we don't have to managed it ourselves
-  // Note: Normally this would be in the form of an actual database and not part of the Dao Impl.
-  private List<Customer> customers;
-
-  public CustomerDaoImpl(final List<Customer> customers) {
-    this.customers = customers;
-  }
-
-  @Override
-  public List<Customer> getAllCustomers() {
-    return customers;
-  }
-
-  @Override
-  public Customer getCustomerById(final int id) {
-    Customer customer = null;
-    for (final Customer cus : getAllCustomers()) {
-      if (cus.getId() == id) {
-        customer = cus;
-        break;
-      }
-    }
-    return customer;
-  }
-
-  @Override
-  public void addCustomer(final Customer customer) {
-    if (getCustomerById(customer.getId()) == null) {
-      customers.add(customer);
-    }
-  }
-
-
-  @Override
-  public void updateCustomer(final Customer customer) {
-    if (getAllCustomers().contains(customer)) {
-      final int index = getAllCustomers().indexOf(customer);
-      getAllCustomers().set(index, customer);
-    }
-  }
-
-  @Override
-  public void deleteCustomer(final Customer customer) {
-    getAllCustomers().remove(customer);
-  }
-}

dao/src/main/java/com/iluwatar/dao/CustomerSchemaSql.java

@@ -0,0 +1,9 @@
+package com.iluwatar.dao;
+
+public interface CustomerSchemaSql {
+
+  String CREATE_SCHEMA_SQL = "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), " 
+      + "LNAME VARCHAR(100))";
+  
+  String DELETE_SCHEMA_SQL = "DROP TABLE CUSTOMERS";
+}

dao/src/main/java/com/iluwatar/dao/DbCustomerDao.java

@@ -0,0 +1,183 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+
+package com.iluwatar.dao;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.Optional;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import javax.sql.DataSource;
+
+/**
+ * An implementation of {@link CustomerDao} that persists customers in RDBMS. 
+ *
+ */
+public class DbCustomerDao implements CustomerDao {
+
+  private final DataSource dataSource;
+
+  /**
+   * Creates an instance of {@link DbCustomerDao} which uses provided <code>dataSource</code>
+   * to store and retrieve customer information.
+   * 
+   * @param dataSource a non-null dataSource.
+   */
+  public DbCustomerDao(DataSource dataSource) {
+    this.dataSource = dataSource;
+  }
+
+  /**
+   * @return a lazily populated stream of customers. Note the stream returned must be closed to 
+   *     free all the acquired resources. The stream keeps an open connection to the database till
+   *     it is complete or is closed manually.
+   */
+  @Override
+  public Stream<Customer> getAll() throws Exception {
+
+    Connection connection;
+    try {
+      connection = getConnection();
+      PreparedStatement statement = connection.prepareStatement("SELECT * FROM CUSTOMERS");
+      ResultSet resultSet = statement.executeQuery();
+      return StreamSupport.stream(new Spliterators.AbstractSpliterator<Customer>(Long.MAX_VALUE, 
+          Spliterator.ORDERED) {
+
+        @Override
+        public boolean tryAdvance(Consumer<? super Customer> action) {
+          try {
+            if (!resultSet.next()) {
+              return false;
+            }
+            action.accept(createCustomer(resultSet));
+            return true;
+          } catch (SQLException e) {
+            throw new RuntimeException(e);
+          }
+        }
+      }, false).onClose(() -> mutedClose(connection));
+    } catch (SQLException e) {
+      throw new Exception(e.getMessage(), e);
+    }
+  }
+
+  private Connection getConnection() throws SQLException {
+    return dataSource.getConnection();
+  }
+
+  private void mutedClose(Connection connection) {
+    try {
+      connection.close();
+    } catch (SQLException e) {
+      e.printStackTrace();
+    }
+  }
+
+  private Customer createCustomer(ResultSet resultSet) throws SQLException {
+    return new Customer(resultSet.getInt("ID"), 
+        resultSet.getString("FNAME"), 
+        resultSet.getString("LNAME"));
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public Optional<Customer> getById(int id) throws Exception {
+    try (Connection connection = getConnection();
+        PreparedStatement statement = 
+            connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
+
+      statement.setInt(1, id);
+      ResultSet resultSet = statement.executeQuery();
+      if (resultSet.next()) {
+        return Optional.of(createCustomer(resultSet));
+      } else {
+        return Optional.empty();
+      }
+    } catch (SQLException ex) {
+      throw new Exception(ex.getMessage(), ex);
+    }
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public boolean add(Customer customer) throws Exception {
+    if (getById(customer.getId()).isPresent()) {
+      return false;
+    }
+
+    try (Connection connection = getConnection();
+        PreparedStatement statement = 
+            connection.prepareStatement("INSERT INTO CUSTOMERS VALUES (?,?,?)")) {
+      statement.setInt(1, customer.getId());
+      statement.setString(2, customer.getFirstName());
+      statement.setString(3, customer.getLastName());
+      statement.execute();
+      return true;
+    } catch (SQLException ex) {
+      throw new Exception(ex.getMessage(), ex);
+    }
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public boolean update(Customer customer) throws Exception {
+    try (Connection connection = getConnection();
+        PreparedStatement statement = 
+            connection.prepareStatement("UPDATE CUSTOMERS SET FNAME = ?, LNAME = ? WHERE ID = ?")) {
+      statement.setString(1, customer.getFirstName());
+      statement.setString(2, customer.getLastName());
+      statement.setInt(3, customer.getId());
+      return statement.executeUpdate() > 0;
+    } catch (SQLException ex) {
+      throw new Exception(ex.getMessage(), ex);
+    }
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public boolean delete(Customer customer) throws Exception {
+    try (Connection connection = getConnection();
+        PreparedStatement statement = 
+            connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
+      statement.setInt(1, customer.getId());
+      return statement.executeUpdate() > 0;
+    } catch (SQLException ex) {
+      throw new Exception(ex.getMessage(), ex);
+    }
+  }
+}

dao/src/main/java/com/iluwatar/dao/InMemoryCustomerDao.java

@@ -0,0 +1,73 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+
+package com.iluwatar.dao;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+/**
+ * An in memory implementation of {@link CustomerDao}, which stores the customers in JVM memory
+ * and data is lost when the application exits.
+ * <br/>
+ * This implementation is useful as temporary database or for testing.
+ */
+public class InMemoryCustomerDao implements CustomerDao {
+
+  private Map<Integer, Customer> idToCustomer = new HashMap<>();
+
+  /**
+   * An eagerly evaluated stream of customers stored in memory.
+   */
+  @Override
+  public Stream<Customer> getAll() {
+    return idToCustomer.values().stream();
+  }
+
+  @Override
+  public Optional<Customer> getById(final int id) {
+    return Optional.ofNullable(idToCustomer.get(id));
+  }
+
+  @Override
+  public boolean add(final Customer customer) {
+    if (getById(customer.getId()).isPresent()) {
+      return false;
+    }
+    
+    idToCustomer.put(customer.getId(), customer);
+    return true;
+  }
+
+  @Override
+  public boolean update(final Customer customer) {
+    return idToCustomer.replace(customer.getId(), customer) != null;
+  }
+
+  @Override
+  public boolean delete(final Customer customer) {
+    return idToCustomer.remove(customer.getId()) != null;
+  }
+}

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

@@ -20,18 +20,17 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
 import org.junit.Test;
 
-import java.io.IOException;
-
 /**
  * Tests that DAO example runs without errors.
  */
 public class AppTest {
   @Test
-  public void test() throws IOException {
+  public void test() throws Exception {
     String[] args = {};
     App.main(args);
   }

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

@@ -1,121 +0,0 @@
-/**
- * The MIT License
- * Copyright (c) 2014 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.
- */
-package com.iluwatar.dao;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import org.junit.Before;
-import org.junit.Test;
-
-public class CustomerDaoImplTest {
-
-  private CustomerDaoImpl impl;
-  private List<Customer> customers;
-  private static final Customer CUSTOMER = new Customer(1, "Freddy", "Krueger");
-
-  @Before
-  public void setUp() {
-    customers = new ArrayList<>();
-    customers.add(CUSTOMER);
-    impl = new CustomerDaoImpl(customers);
-  }
-
-  @Test
-  public void deleteExistingCustomer() {
-    assertEquals(1, impl.getAllCustomers().size());
-    impl.deleteCustomer(CUSTOMER);
-    assertTrue(impl.getAllCustomers().isEmpty());
-  }
-
-  @Test
-  public void deleteNonExistingCustomer() {
-    final Customer nonExistingCustomer = new Customer(2, "Robert", "Englund");
-    impl.deleteCustomer(nonExistingCustomer);
-    assertEquals(1, impl.getAllCustomers().size());
-  }
-
-  @Test
-  public void updateExistingCustomer() {
-    final String newFirstname = "Bernard";
-    final String newLastname = "Montgomery";
-    final Customer customer = new Customer(CUSTOMER.getId(), newFirstname, newLastname);
-    impl.updateCustomer(customer);
-    final Customer cust = impl.getCustomerById(CUSTOMER.getId());
-    assertEquals(newFirstname, cust.getFirstName());
-    assertEquals(newLastname, cust.getLastName());
-  }
-
-  @Test
-  public void updateNonExistingCustomer() {
-    final int nonExistingId = getNonExistingCustomerId();
-    final String newFirstname = "Douglas";
-    final String newLastname = "MacArthur";
-    final Customer customer = new Customer(nonExistingId, newFirstname, newLastname);
-    impl.updateCustomer(customer);
-    assertNull(impl.getCustomerById(nonExistingId));
-    final Customer existingCustomer = impl.getCustomerById(CUSTOMER.getId());
-    assertEquals(CUSTOMER.getFirstName(), existingCustomer.getFirstName());
-    assertEquals(CUSTOMER.getLastName(), existingCustomer.getLastName());
-  }
-
-  @Test
-  public void addCustomer() {
-    final Customer newCustomer = new Customer(3, "George", "Patton");
-    impl.addCustomer(newCustomer);
-    assertEquals(2, impl.getAllCustomers().size());
-  }
-
-  @Test
-  public void addAlreadyAddedCustomer() {
-    final Customer newCustomer = new Customer(3, "George", "Patton");
-    impl.addCustomer(newCustomer);
-    assertEquals(2, impl.getAllCustomers().size());
-    impl.addCustomer(newCustomer);
-    assertEquals(2, impl.getAllCustomers().size());
-  }
-
-  @Test
-  public void getExistinCustomerById() {
-    assertEquals(CUSTOMER, impl.getCustomerById(CUSTOMER.getId()));
-  }
-
-  @Test
-  public void getNonExistinCustomerById() {
-    final int nonExistingId = getNonExistingCustomerId();
-    assertNull(impl.getCustomerById(nonExistingId));
-  }
-
-  /**
-   * An arbitrary number which does not correspond to an active Customer id.
-   * 
-   * @return an int of a customer id which doesn't exist
-   */
-  private int getNonExistingCustomerId() {
-    return 999;
-  }
-}

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

@@ -20,6 +20,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
 import static org.junit.Assert.assertEquals;

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

@@ -0,0 +1,247 @@
+package com.iluwatar.dao;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.stream.Stream;
+
+import javax.sql.DataSource;
+
+import org.h2.jdbcx.JdbcDataSource;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+import org.mockito.Mockito;
+
+import de.bechte.junit.runners.context.HierarchicalContextRunner;
+
+/**
+ * Tests {@link DbCustomerDao}.
+ */
+@RunWith(HierarchicalContextRunner.class)
+public class DbCustomerDaoTest {
+
+  private static final String DB_URL = "jdbc:h2:~/dao:customerdb";
+  private DbCustomerDao dao;
+  private Customer existingCustomer = new Customer(1, "Freddy", "Krueger");
+
+  /**
+   * Creates customers schema.
+   * @throws SQLException if there is any error while creating schema.
+   */
+  @Before
+  public void createSchema() throws SQLException {
+    try (Connection connection = DriverManager.getConnection(DB_URL);
+        Statement statement = connection.createStatement()) {
+      statement.execute(CustomerSchemaSql.CREATE_SCHEMA_SQL);
+    }
+  }
+
+  /**
+   * Represents the scenario where DB connectivity is present.
+   */
+  public class ConnectionSuccess {
+
+    /**
+     * Setup for connection success scenario.
+     * @throws Exception if any error occurs.
+     */
+    @Before
+    public void setUp() throws Exception {
+      JdbcDataSource dataSource = new JdbcDataSource();
+      dataSource.setURL(DB_URL);
+      dao = new DbCustomerDao(dataSource);
+      boolean result = dao.add(existingCustomer);
+      assertTrue(result);
+    }
+
+    /**
+     * Represents the scenario when DAO operations are being performed on a non existing customer.
+     */
+    public class NonExistingCustomer {
+
+      @Test
+      public void addingShouldResultInSuccess() throws Exception {
+        try (Stream<Customer> allCustomers = dao.getAll()) {
+          assumeTrue(allCustomers.count() == 1);
+        }
+
+        final Customer nonExistingCustomer = new Customer(2, "Robert", "Englund");
+        boolean result = dao.add(nonExistingCustomer);
+        assertTrue(result);
+
+        assertCustomerCountIs(2);
+        assertEquals(nonExistingCustomer, dao.getById(nonExistingCustomer.getId()).get());
+      }
+
+      @Test
+      public void deletionShouldBeFailureAndNotAffectExistingCustomers() throws Exception {
+        final Customer nonExistingCustomer = new Customer(2, "Robert", "Englund");
+        boolean result = dao.delete(nonExistingCustomer);
+
+        assertFalse(result);
+        assertCustomerCountIs(1);
+      }
+
+      @Test
+      public void updationShouldBeFailureAndNotAffectExistingCustomers() throws Exception {
+        final int nonExistingId = getNonExistingCustomerId();
+        final String newFirstname = "Douglas";
+        final String newLastname = "MacArthur";
+        final Customer customer = new Customer(nonExistingId, newFirstname, newLastname);
+        boolean result = dao.update(customer);
+
+        assertFalse(result);
+        assertFalse(dao.getById(nonExistingId).isPresent());
+      }
+
+      @Test
+      public void retrieveShouldReturnNoCustomer() throws Exception {
+        assertFalse(dao.getById(getNonExistingCustomerId()).isPresent());
+      }
+    }
+
+    /**
+     * Represents a scenario where DAO operations are being performed on an already existing
+     * customer.
+     *
+     */
+    public class ExistingCustomer {
+
+      @Test
+      public void addingShouldResultInFailureAndNotAffectExistingCustomers() throws Exception {
+        Customer existingCustomer = new Customer(1, "Freddy", "Krueger");
+
+        boolean result = dao.add(existingCustomer);
+
+        assertFalse(result);
+        assertCustomerCountIs(1);
+        assertEquals(existingCustomer, dao.getById(existingCustomer.getId()).get());
+      }
+
+      @Test
+      public void deletionShouldBeSuccessAndCustomerShouldBeNonAccessible() throws Exception {
+        boolean result = dao.delete(existingCustomer);
+
+        assertTrue(result);
+        assertCustomerCountIs(0);
+        assertFalse(dao.getById(existingCustomer.getId()).isPresent());
+      }
+
+      @Test
+      public void updationShouldBeSuccessAndAccessingTheSameCustomerShouldReturnUpdatedInformation() throws Exception {
+        final String newFirstname = "Bernard";
+        final String newLastname = "Montgomery";
+        final Customer customer = new Customer(existingCustomer.getId(), newFirstname, newLastname);
+        boolean result = dao.update(customer);
+
+        assertTrue(result);
+
+        final Customer cust = dao.getById(existingCustomer.getId()).get();
+        assertEquals(newFirstname, cust.getFirstName());
+        assertEquals(newLastname, cust.getLastName());
+      }
+    }
+  }
+
+  /**
+   * Represents a scenario where DB connectivity is not present due to network issue, or
+   * DB service unavailable.
+   * 
+   */
+  public class ConnectivityIssue {
+    
+    private static final String EXCEPTION_CAUSE = "Connection not available";
+    @Rule public ExpectedException exception = ExpectedException.none();
+    
+    /**
+     * setup a connection failure scenario.
+     * @throws SQLException if any error occurs.
+     */
+    @Before
+    public void setUp() throws SQLException {
+      dao = new DbCustomerDao(mockedDatasource());
+      exception.expect(Exception.class);
+      exception.expectMessage(EXCEPTION_CAUSE);
+    }
+    
+    private DataSource mockedDatasource() throws SQLException {
+      DataSource mockedDataSource = mock(DataSource.class);
+      Connection mockedConnection = mock(Connection.class);
+      SQLException exception = new SQLException(EXCEPTION_CAUSE);
+      doThrow(exception).when(mockedConnection).prepareStatement(Mockito.anyString());
+      doReturn(mockedConnection).when(mockedDataSource).getConnection();
+      return mockedDataSource;
+    }
+
+    @Test
+    public void addingACustomerFailsWithExceptionAsFeedbackToClient() throws Exception {
+      dao.add(new Customer(2, "Bernard", "Montgomery"));
+    }
+    
+    @Test
+    public void deletingACustomerFailsWithExceptionAsFeedbackToTheClient() throws Exception {
+      dao.delete(existingCustomer);
+    }
+    
+    @Test
+    public void updatingACustomerFailsWithFeedbackToTheClient() throws Exception {
+      final String newFirstname = "Bernard";
+      final String newLastname = "Montgomery";
+      
+      dao.update(new Customer(existingCustomer.getId(), newFirstname, newLastname));
+    }
+    
+    @Test
+    public void retrievingACustomerByIdFailsWithExceptionAsFeedbackToClient() throws Exception {
+      dao.getById(existingCustomer.getId());
+    }
+    
+    @Test
+    public void retrievingAllCustomersFailsWithExceptionAsFeedbackToClient() throws Exception {
+      dao.getAll();
+    }
+
+  }
+
+  /**
+   * Delete customer schema for fresh setup per test.
+   * @throws SQLException if any error occurs.
+   */
+  @After
+  public void deleteSchema() throws SQLException {
+    try (Connection connection = DriverManager.getConnection(DB_URL);
+        Statement statement = connection.createStatement()) {
+      statement.execute(CustomerSchemaSql.DELETE_SCHEMA_SQL);
+    }
+  }
+
+  private void assertCustomerCountIs(int count) throws Exception {
+    try (Stream<Customer> allCustomers = dao.getAll()) {
+      assertTrue(allCustomers.count() == count);
+    }
+  }
+
+
+  /**
+   * An arbitrary number which does not correspond to an active Customer id.
+   * 
+   * @return an int of a customer id which doesn't exist
+   */
+  private int getNonExistingCustomerId() {
+    return 999;
+  }
+}

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

@@ -0,0 +1,164 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+
+package com.iluwatar.dao;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
+
+import java.util.Optional;
+import java.util.stream.Stream;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import de.bechte.junit.runners.context.HierarchicalContextRunner;
+
+/**
+ * Tests {@link InMemoryCustomerDao}.
+ */
+@RunWith(HierarchicalContextRunner.class)
+public class InMemoryCustomerDaoTest {
+
+  private InMemoryCustomerDao dao;
+  private static final Customer CUSTOMER = new Customer(1, "Freddy", "Krueger");
+
+  @Before
+  public void setUp() {
+    dao = new InMemoryCustomerDao();
+    assertTrue(dao.add(CUSTOMER));
+  }
+
+  /**
+   * Represents the scenario when the DAO operations are being performed on a non existent 
+   * customer.  
+   */
+  public class NonExistingCustomer {
+
+    @Test
+    public void addingShouldResultInSuccess() throws Exception {
+      try (Stream<Customer> allCustomers = dao.getAll()) {
+        assumeTrue(allCustomers.count() == 1);
+      }
+
+      final Customer nonExistingCustomer = new Customer(2, "Robert", "Englund");
+      boolean result = dao.add(nonExistingCustomer);
+      assertTrue(result);
+
+      assertCustomerCountIs(2);
+      assertEquals(nonExistingCustomer, dao.getById(nonExistingCustomer.getId()).get());
+    }
+
+    @Test
+    public void deletionShouldBeFailureAndNotAffectExistingCustomers() throws Exception {
+      final Customer nonExistingCustomer = new Customer(2, "Robert", "Englund");
+      boolean result = dao.delete(nonExistingCustomer);
+
+      assertFalse(result);
+      assertCustomerCountIs(1);
+    }
+
+    @Test
+    public void updationShouldBeFailureAndNotAffectExistingCustomers() throws Exception {
+      final int nonExistingId = getNonExistingCustomerId();
+      final String newFirstname = "Douglas";
+      final String newLastname = "MacArthur";
+      final Customer customer = new Customer(nonExistingId, newFirstname, newLastname);
+      boolean result = dao.update(customer);
+
+      assertFalse(result);
+      assertFalse(dao.getById(nonExistingId).isPresent());
+    }
+
+    @Test
+    public void retrieveShouldReturnNoCustomer() throws Exception {
+      assertFalse(dao.getById(getNonExistingCustomerId()).isPresent());
+    }
+  }
+
+  /**
+   * Represents the scenario when the DAO operations are being performed on an already existing
+   * customer.
+   */
+  public class ExistingCustomer {
+
+    @Test
+    public void addingShouldResultInFailureAndNotAffectExistingCustomers() throws Exception {
+      boolean result = dao.add(CUSTOMER);
+
+      assertFalse(result);
+      assertCustomerCountIs(1);
+      assertEquals(CUSTOMER, dao.getById(CUSTOMER.getId()).get());
+    }
+
+    @Test
+    public void deletionShouldBeSuccessAndCustomerShouldBeNonAccessible() throws Exception {
+      boolean result = dao.delete(CUSTOMER);
+
+      assertTrue(result);
+      assertCustomerCountIs(0);
+      assertFalse(dao.getById(CUSTOMER.getId()).isPresent());
+    }
+
+    @Test
+    public void updationShouldBeSuccessAndAccessingTheSameCustomerShouldReturnUpdatedInformation() throws Exception {
+      final String newFirstname = "Bernard";
+      final String newLastname = "Montgomery";
+      final Customer customer = new Customer(CUSTOMER.getId(), newFirstname, newLastname);
+      boolean result = dao.update(customer);
+
+      assertTrue(result);
+
+      final Customer cust = dao.getById(CUSTOMER.getId()).get();
+      assertEquals(newFirstname, cust.getFirstName());
+      assertEquals(newLastname, cust.getLastName());
+    }
+    
+    @Test
+    public void retriveShouldReturnTheCustomer() {
+      Optional<Customer> optionalCustomer = dao.getById(CUSTOMER.getId());
+      
+      assertTrue(optionalCustomer.isPresent());
+      assertEquals(CUSTOMER, optionalCustomer.get());
+    }
+  }
+
+  /**
+   * An arbitrary number which does not correspond to an active Customer id.
+   * 
+   * @return an int of a customer id which doesn't exist
+   */
+  private int getNonExistingCustomerId() {
+    return 999;
+  }
+  
+  private void assertCustomerCountIs(int count) throws Exception {
+    try (Stream<Customer> allCustomers = dao.getAll()) {
+      assertTrue(allCustomers.count() == count);
+    }
+  }
+}

decorator/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>decorator</artifactId>
   <dependencies>

decorator/src/main/java/com/iluwatar/decorator/Troll.java

@@ -29,6 +29,7 @@ package com.iluwatar.decorator;
  */
 public class Troll implements Hostile {
 
+  @Override
   public void attack() {
     System.out.println("The troll swings at you with a club!");
   }
@@ -38,6 +39,7 @@ public class Troll implements Hostile {
     return 10;
   }
 
+  @Override
   public void fleeBattle() {
     System.out.println("The troll shrieks in horror and runs away!");
   }

delegation/pom.xml

@@ -30,7 +30,7 @@
     <parent>
         <artifactId>java-design-patterns</artifactId>
         <groupId>com.iluwatar</groupId>
-        <version>1.10.0</version>
+        <version>1.11.0</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 

dependency-injection/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>dependency-injection</artifactId>
   <dependencies>

double-checked-locking/pom.xml

@@ -27,7 +27,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>double-checked-locking</artifactId>
   <dependencies>

double-dispatch/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>double-dispatch</artifactId>
   <dependencies>

event-aggregator/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>com.iluwatar</groupId>
 		<artifactId>java-design-patterns</artifactId>
-		<version>1.10.0</version>
+		<version>1.11.0</version>
 	</parent>
 	<artifactId>event-aggregator</artifactId>
 	<dependencies>

event-aggregator/src/main/java/com/iluwatar/event/aggregator/EventEmitter.java

@@ -43,7 +43,7 @@ public abstract class EventEmitter {
     registerObserver(obs);
   }
 
-  public void registerObserver(EventObserver obs) {
+  public final void registerObserver(EventObserver obs) {
     observers.add(obs);
   }
 

event-driven-architecture/etc/eda.ucls

@@ -4,7 +4,7 @@
   <class id="1" language="java" name="com.iluwatar.eda.model.User" project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/model/User.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="937" y="618"/>    
+    <position height="-1" width="-1" x="437" y="535"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -15,7 +15,7 @@
     project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/handler/UserUpdatedEventHandler.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="936" y="90"/>    
+    <position height="-1" width="-1" x="763" y="379"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -26,17 +26,17 @@
     project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/handler/UserCreatedEventHandler.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="101" width="200" x="41" y="37"/>    
+    <position height="-1" width="-1" x="596" y="272"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <interface id="4" language="java" name="com.iluwatar.eda.framework.Message" project="event-driven-architecture" 
-    file="/event-driven-architecture/src/main/java/com/iluwatar/eda/framework/Message.java" binary="false" 
+  <interface id="4" language="java" name="com.iluwatar.eda.framework.Event" project="event-driven-architecture" 
+    file="/event-driven-architecture/src/main/java/com/iluwatar/eda/framework/Event.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="298" y="189"/>    
+    <position height="-1" width="-1" x="188" y="121"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -46,7 +46,7 @@
   <interface id="5" language="java" name="com.iluwatar.eda.framework.Handler" project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/framework/Handler.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="532" y="89"/>    
+    <position height="-1" width="-1" x="755" y="58"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -56,7 +56,7 @@
   <class id="6" language="java" name="com.iluwatar.eda.framework.EventDispatcher" project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/framework/EventDispatcher.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="613" y="292"/>    
+    <position height="-1" width="-1" x="499" y="122"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -66,7 +66,7 @@
   <class id="7" language="java" name="com.iluwatar.eda.event.UserCreatedEvent" project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/event/UserCreatedEvent.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="145" y="618"/>    
+    <position height="-1" width="-1" x="102" y="380"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -76,17 +76,17 @@
   <class id="8" language="java" name="com.iluwatar.eda.event.UserUpdatedEvent" project="event-driven-architecture" 
     file="/event-driven-architecture/src/main/java/com/iluwatar/eda/event/UserUpdatedEvent.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="769" y="455"/>    
+    <position height="-1" width="-1" x="320" y="382"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </class>  
-  <class id="9" language="java" name="com.iluwatar.eda.event.Event" project="event-driven-architecture" 
-    file="/event-driven-architecture/src/main/java/com/iluwatar/eda/event/Event.java" binary="false" 
+  <class id="9" language="java" name="com.iluwatar.eda.event.AbstractEvent" project="event-driven-architecture" 
+    file="/event-driven-architecture/src/main/java/com/iluwatar/eda/event/AbstractEvent.java" binary="false" 
     corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="299" y="460"/>    
+    <position height="-1" width="-1" x="188" y="240"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
@@ -94,99 +94,87 @@
     </display>  
   </class>  
   <dependency id="10">    
-    <bendpoint x="869" y="253"/>    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="1"/>  
+  </dependency>  
+  <dependency id="11">    
+    <end type="SOURCE" refId="2"/>    
+    <end type="TARGET" refId="1"/>  
+  </dependency>  
+  <dependency id="12">    
     <end type="SOURCE" refId="2"/>    
     <end type="TARGET" refId="8"/>  
   </dependency>  
-  <dependency id="11">    
-    <bendpoint x="140" y="196"/>    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="9"/>  
-  </dependency>  
-  <dependency id="12">    
-    <bendpoint x="17" y="90"/>    
-    <bendpoint x="17" y="708"/>    
-    <bendpoint x="939" y="703"/>    
-    <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="1"/>  
-  </dependency>  
-  <dependency id="13">    
-    <bendpoint x="935" y="318"/>    
-    <bendpoint x="936" y="417"/>    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="1"/>  
-  </dependency>  
-  <dependency id="14">    
-    <bendpoint x="757" y="378"/>    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="9"/>  
-  </dependency>  
-  <generalization id="15">    
-    <end type="SOURCE" refId="7"/>    
-    <end type="TARGET" refId="9"/>  
-  </generalization>  
-  <association id="16">    
-    <end type="SOURCE" refId="8" navigable="false">      
-      <attribute id="17" name="user"/>      
-      <multiplicity id="18" minimum="0" maximum="1"/>    
-    </end>    
-    <end type="TARGET" refId="1" navigable="true"/>    
-    <display labels="true" multiplicity="true"/>  
-  </association>  
-  <realization id="19">    
+  <realization id="13">    
     <end type="SOURCE" refId="2"/>    
     <end type="TARGET" refId="5"/>  
   </realization>  
-  <dependency id="20">    
-    <end type="SOURCE" refId="5"/>    
-    <end type="TARGET" refId="9"/>  
-  </dependency>  
-  <dependency id="21">    
-    <bendpoint x="301" y="114"/>    
-    <end type="SOURCE" refId="5"/>    
-    <end type="TARGET" refId="4"/>  
-  </dependency>  
-  <realization id="22">    
-    <end type="SOURCE" refId="9"/>    
-    <end type="TARGET" refId="4"/>  
-  </realization>  
-  <dependency id="23">    
-    <end type="SOURCE" refId="6"/>    
-    <end type="TARGET" refId="9"/>  
-  </dependency>  
-  <generalization id="24">    
-    <end type="SOURCE" refId="8"/>    
+  <generalization id="14">    
+    <end type="SOURCE" refId="7"/>    
     <end type="TARGET" refId="9"/>  
   </generalization>  
-  <dependency id="25">    
-    <bendpoint x="141" y="250"/>    
+  <realization id="15">    
     <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="7"/>  
-  </dependency>  
-  <association id="26">    
+    <end type="TARGET" refId="5"/>  
+  </realization>  
+  <association id="16">    
     <end type="SOURCE" refId="6" navigable="false">      
-      <attribute id="27" name="handlers">        
-        <position height="19" width="56" x="449" y="175"/>      
+      <attribute id="17" name="handlers">        
+        <position height="19" width="56" x="672" y="144"/>      
       </attribute>      
-      <multiplicity id="28" minimum="0" maximum="2147483647">        
-        <position height="17" width="23" x="574" y="173"/>      
+      <multiplicity id="18" minimum="0" maximum="2147483647">        
+        <position height="17" width="23" x="797" y="142"/>      
       </multiplicity>    
     </end>    
     <end type="TARGET" refId="5" navigable="true"/>    
     <display labels="true" multiplicity="true"/>  
   </association>  
-  <association id="29">    
-    <end type="SOURCE" refId="7" navigable="false">      
-      <attribute id="30" name="user"/>      
-      <multiplicity id="31" minimum="0" maximum="1"/>    
+  <realization id="19">    
+    <end type="SOURCE" refId="9"/>    
+    <end type="TARGET" refId="4"/>  
+  </realization>  
+  <dependency id="20">    
+    <end type="SOURCE" refId="6"/>    
+    <end type="TARGET" refId="4"/>  
+  </dependency>  
+  <dependency id="21">    
+    <bendpoint x="187" y="57"/>    
+    <end type="SOURCE" refId="5"/>    
+    <end type="TARGET" refId="4"/>  
+  </dependency>  
+  <association id="22">    
+    <end type="SOURCE" refId="8" navigable="false">      
+      <attribute id="23" name="user">        
+        <position height="0" width="0" x="-500" y="-83"/>      
+      </attribute>      
+      <multiplicity id="24" minimum="0" maximum="1">        
+        <position height="0" width="0" x="-500" y="-83"/>      
+      </multiplicity>    
     </end>    
     <end type="TARGET" refId="1" navigable="true"/>    
     <display labels="true" multiplicity="true"/>  
   </association>  
-  <realization id="32">    
+  <generalization id="25">    
+    <end type="SOURCE" refId="8"/>    
+    <end type="TARGET" refId="9"/>  
+  </generalization>  
+  <association id="26">    
+    <end type="SOURCE" refId="7" navigable="false">      
+      <attribute id="27" name="user">        
+        <position height="0" width="0" x="-500" y="-83"/>      
+      </attribute>      
+      <multiplicity id="28" minimum="0" maximum="1">        
+        <position height="0" width="0" x="-500" y="-83"/>      
+      </multiplicity>    
+    </end>    
+    <end type="TARGET" refId="1" navigable="true"/>    
+    <display labels="true" multiplicity="true"/>  
+  </association>  
+  <dependency id="29">    
+    <bendpoint x="308" y="303"/>    
     <end type="SOURCE" refId="3"/>    
-    <end type="TARGET" refId="5"/>  
-  </realization>  
+    <end type="TARGET" refId="7"/>  
+  </dependency>  
   <classifier-display autosize="true" stereotype="true" package="true" initial-value="true" signature="true" 
     sort-features="false" accessors="true" visibility="true">    
     <attributes public="true" package="true" protected="true" private="true" static="true"/>    

event-driven-architecture/pom.xml

@@ -31,7 +31,7 @@
     <parent>
         <groupId>com.iluwatar</groupId>
         <artifactId>java-design-patterns</artifactId>
-        <version>1.10.0</version>
+        <version>1.11.0</version>
     </parent>
 
     <artifactId>event-driven-architecture</artifactId>

event-driven-architecture/src/main/java/com/iluwatar/eda/App.java

@@ -22,9 +22,9 @@
  */
 package com.iluwatar.eda;
 
-import com.iluwatar.eda.event.Event;
 import com.iluwatar.eda.event.UserCreatedEvent;
 import com.iluwatar.eda.event.UserUpdatedEvent;
+import com.iluwatar.eda.framework.Event;
 import com.iluwatar.eda.framework.EventDispatcher;
 import com.iluwatar.eda.handler.UserCreatedEventHandler;
 import com.iluwatar.eda.handler.UserUpdatedEventHandler;
@@ -53,12 +53,12 @@ public class App {
   public static void main(String[] args) {
 
     EventDispatcher dispatcher = new EventDispatcher();
-    dispatcher.registerChannel(UserCreatedEvent.class, new UserCreatedEventHandler());
-    dispatcher.registerChannel(UserUpdatedEvent.class, new UserUpdatedEventHandler());
+    dispatcher.registerHandler(UserCreatedEvent.class, new UserCreatedEventHandler());
+    dispatcher.registerHandler(UserUpdatedEvent.class, new UserUpdatedEventHandler());
 
     User user = new User("iluwatar");
-    dispatcher.onEvent(new UserCreatedEvent(user));
-    dispatcher.onEvent(new UserUpdatedEvent(user));
+    dispatcher.dispatch(new UserCreatedEvent(user));
+    dispatcher.dispatch(new UserUpdatedEvent(user));
   }
 
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/event/AbstractEvent.java

@@ -23,10 +23,10 @@
 package com.iluwatar.eda.event;
 
 import com.iluwatar.eda.framework.EventDispatcher;
-import com.iluwatar.eda.framework.Message;
+import com.iluwatar.eda.framework.Event;
 
 /**
- * The {@link Event} class serves as a base class for defining custom events happening with your
+ * The {@link AbstractEvent} class serves as a base class for defining custom events happening with your
  * system. In this example we have two types of events defined.
  * <ul>
  *   <li>{@link UserCreatedEvent} - used when a user is created</li>
@@ -34,16 +34,16 @@ import com.iluwatar.eda.framework.Message;
  * </ul>
  * Events can be distinguished using the {@link #getType() getType} method.
  */
-public class Event implements Message {
+public abstract class AbstractEvent implements Event {
 
   /**
    * Returns the event type as a {@link Class} object
    * In this example, this method is used by the {@link EventDispatcher} to
    * dispatch events depending on their type.
    *
-   * @return the Event type as a {@link Class}.
+   * @return the AbstractEvent type as a {@link Class}.
    */
-  public Class<? extends Message> getType() {
+  public Class<? extends Event> getType() {
     return getClass();
   }
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/event/UserCreatedEvent.java

@@ -29,7 +29,7 @@ import com.iluwatar.eda.model.User;
  * This class can be extended to contain details about the user has been created. In this example,
  * the entire {@link User} object is passed on as data with the event.
  */
-public class UserCreatedEvent extends Event {
+public class UserCreatedEvent extends AbstractEvent {
 
   private User user;
 

event-driven-architecture/src/main/java/com/iluwatar/eda/event/UserUpdatedEvent.java

@@ -29,7 +29,7 @@ import com.iluwatar.eda.model.User;
  * This class can be extended to contain details about the user has been updated. In this example,
  * the entire {@link User} object is passed on as data with the event.
  */
-public class UserUpdatedEvent extends Event {
+public class UserUpdatedEvent extends AbstractEvent {
 
   private User user;
 

event-driven-architecture/src/main/java/com/iluwatar/eda/framework/Event.java

@@ -23,15 +23,15 @@
 package com.iluwatar.eda.framework;
 
 /**
- * A {@link Message} is an object with a specific type that is associated
+ * A {@link Event} is an object with a specific type that is associated
  * to a specific {@link Handler}.
  */
-public interface Message {
+public interface Event {
 
   /**
    * Returns the message type as a {@link Class} object. In this example the message type is
    * used to handle events by their type.
    * @return the message type as a {@link Class}.
    */
-  Class<? extends Message> getType();
+  Class<? extends Event> getType();
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/framework/EventDispatcher.java

@@ -22,19 +22,16 @@
  */
 package com.iluwatar.eda.framework;
 
-import com.iluwatar.eda.event.Event;
-
 import java.util.HashMap;
 import java.util.Map;
 
 /**
  * Handles the routing of {@link Event} messages to associated handlers.
  * A {@link HashMap} is used to store the association between events and their respective handlers.
- *
  */
 public class EventDispatcher {
 
-  private Map<Class<? extends Event>, Handler<?>> handlers;
+  private Map<Class<? extends Event>, Handler<? extends Event>> handlers;
 
   public EventDispatcher() {
     handlers = new HashMap<>();
@@ -46,8 +43,8 @@ public class EventDispatcher {
    * @param eventType The {@link Event} to be registered
    * @param handler   The {@link Handler} that will be handling the {@link Event}
    */
-  public void registerChannel(Class<? extends Event> eventType,
-                              Handler<?> handler) {
+  public <E extends Event> void registerHandler(Class<E> eventType,
+                                                Handler<E> handler) {
     handlers.put(eventType, handler);
   }
 
@@ -56,8 +53,12 @@ public class EventDispatcher {
    *
    * @param event The {@link Event} to be dispatched
    */
-  public void onEvent(Event event) {
-    handlers.get(event.getClass()).onEvent(event);
+  @SuppressWarnings("unchecked")
+  public <E extends Event> void dispatch(E event) {
+    Handler<E> handler = (Handler<E>) handlers.get(event.getClass());
+    if (handler != null) {
+      handler.onEvent(event);
+    }
   }
 
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/framework/Handler.java

@@ -22,13 +22,11 @@
  */
 package com.iluwatar.eda.framework;
 
-import com.iluwatar.eda.event.Event;
-
 /**
  * This interface can be implemented to handle different types of messages.
  * Every handler is responsible for a single of type message
  */
-public interface Handler<E extends Message> {
+public interface Handler<E extends Event> {
 
   /**
    * The onEvent method should implement and handle behavior related to the event.
@@ -36,5 +34,5 @@ public interface Handler<E extends Message> {
    * a queue to be consumed by other sub systems.
    * @param event the {@link Event} object to be handled.
    */
-  void onEvent(Event event);
+  void onEvent(E event);
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/handler/UserCreatedEventHandler.java

@@ -22,7 +22,6 @@
  */
 package com.iluwatar.eda.handler;
 
-import com.iluwatar.eda.event.Event;
 import com.iluwatar.eda.event.UserCreatedEvent;
 import com.iluwatar.eda.framework.Handler;
 
@@ -32,9 +31,10 @@ import com.iluwatar.eda.framework.Handler;
 public class UserCreatedEventHandler implements Handler<UserCreatedEvent> {
 
   @Override
-  public void onEvent(Event message) {
+  public void onEvent(UserCreatedEvent event) {
 
-    UserCreatedEvent userCreatedEvent = (UserCreatedEvent) message;
-    System.out.printf("User with %s has been Created!", userCreatedEvent.getUser().getUsername());
+    System.out.println(String.format(
+            "User '%s' has been Created!", event.getUser().getUsername()));
   }
+
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/handler/UserUpdatedEventHandler.java

@@ -22,7 +22,6 @@
  */
 package com.iluwatar.eda.handler;
 
-import com.iluwatar.eda.event.Event;
 import com.iluwatar.eda.event.UserUpdatedEvent;
 import com.iluwatar.eda.framework.Handler;
 
@@ -32,9 +31,9 @@ import com.iluwatar.eda.framework.Handler;
 public class UserUpdatedEventHandler implements Handler<UserUpdatedEvent> {
 
   @Override
-  public void onEvent(Event message) {
+  public void onEvent(UserUpdatedEvent event) {
 
-    UserUpdatedEvent userUpdatedEvent = (UserUpdatedEvent) message;
-    System.out.printf("User with %s has been Updated!", userUpdatedEvent.getUser().getUsername());
+    System.out.println(String.format(
+            "User '%s' has been Updated!", event.getUser().getUsername()));
   }
 }

event-driven-architecture/src/test/java/com/iluwatar/eda/event/UserCreatedEventTest.java

@@ -29,13 +29,13 @@ import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 
 /**
- * {@link UserCreatedEventTest} tests and verifies {@link Event} behaviour.
+ * {@link UserCreatedEventTest} tests and verifies {@link AbstractEvent} behaviour.
  */
 public class UserCreatedEventTest {
 
   /**
-   * This unit test should correctly return the {@link Event} class type when calling the
-   * {@link Event#getType() getType} method.
+   * This unit test should correctly return the {@link AbstractEvent} class type when calling the
+   * {@link AbstractEvent#getType() getType} method.
    */
   @Test
   public void testGetEventType() {

event-driven-architecture/src/test/java/com/iluwatar/eda/framework/EventDispatcherTest.java

@@ -22,7 +22,6 @@
  */
 package com.iluwatar.eda.framework;
 
-import com.iluwatar.eda.framework.EventDispatcher;
 import com.iluwatar.eda.event.UserCreatedEvent;
 import com.iluwatar.eda.event.UserUpdatedEvent;
 import com.iluwatar.eda.handler.UserCreatedEventHandler;
@@ -49,8 +48,8 @@ public class EventDispatcherTest {
     EventDispatcher dispatcher = spy(new EventDispatcher());
     UserCreatedEventHandler userCreatedEventHandler = spy(new UserCreatedEventHandler());
     UserUpdatedEventHandler userUpdatedEventHandler = spy(new UserUpdatedEventHandler());
-    dispatcher.registerChannel(UserCreatedEvent.class, userCreatedEventHandler);
-    dispatcher.registerChannel(UserUpdatedEvent.class, userUpdatedEventHandler);
+    dispatcher.registerHandler(UserCreatedEvent.class, userCreatedEventHandler);
+    dispatcher.registerHandler(UserUpdatedEvent.class, userUpdatedEventHandler);
 
     User user = new User("iluwatar");
 
@@ -58,15 +57,14 @@ public class EventDispatcherTest {
     UserUpdatedEvent userUpdatedEvent = new UserUpdatedEvent(user);
 
     //fire a userCreatedEvent and verify that userCreatedEventHandler has been invoked.
-    dispatcher.onEvent(userCreatedEvent);
+    dispatcher.dispatch(userCreatedEvent);
     verify(userCreatedEventHandler).onEvent(userCreatedEvent);
-    verify(dispatcher).onEvent(userCreatedEvent);
+    verify(dispatcher).dispatch(userCreatedEvent);
 
     //fire a userCreatedEvent and verify that userUpdatedEventHandler has been invoked.
-    dispatcher.onEvent(userUpdatedEvent);
+    dispatcher.dispatch(userUpdatedEvent);
     verify(userUpdatedEventHandler).onEvent(userUpdatedEvent);
-    verify(dispatcher).onEvent(userUpdatedEvent);
+    verify(dispatcher).dispatch(userUpdatedEvent);
   }
 
-
 }

execute-around/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>execute-around</artifactId>
   <dependencies>

facade/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>facade</artifactId>
   <dependencies>

facade/src/main/java/com/iluwatar/facade/DwarvenGoldmineFacade.java

@@ -60,7 +60,7 @@ public class DwarvenGoldmineFacade {
     makeActions(workers, DwarvenMineWorker.Action.GO_HOME, DwarvenMineWorker.Action.GO_TO_SLEEP);
   }
 
-  private void makeActions(Collection<DwarvenMineWorker> workers,
+  private static void makeActions(Collection<DwarvenMineWorker> workers,
       DwarvenMineWorker.Action... actions) {
     for (DwarvenMineWorker worker : workers) {
       worker.action(actions);

factory-kit/README.md

@@ -0,0 +1,28 @@
+---
+layout: pattern
+title: Factory Kit
+folder: factory-kit
+permalink: /patterns/factory-kit/
+categories: Creational
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Functional
+---
+
+## Intent
+Define a factory of immutable content with separated builder and factory interfaces.
+
+![alt text](./etc/factory-kit.png "Factory Kit")
+
+## Applicability
+Use the Factory Kit pattern when
+
+* a class can't anticipate the class of objects it must create
+* you just want a new instance of a custom builder instead of the global one
+* you explicitly want to define types of objects, that factory can build
+* you want a separated builder and creator interface
+
+## Credits
+
+* [Design Pattern Reloaded by Remi Forax: ](https://www.youtube.com/watch?v=-k2X7guaArU)

factory-kit/etc/factory-kit.ucls

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.1.9" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
+  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
+  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+    sort-features="false" accessors="true" visibility="true">    
+    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
+    <operations public="true" package="true" protected="true" private="true" static="true"/>  
+  </classifier-display>  
+  <association-display labels="true" multiplicity="true"/>
+</class-diagram>

factory-kit/pom.xml

@@ -0,0 +1,48 @@
+<?xml version="1.0"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2014 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>1.11.0</version>
+    </parent>
+    <artifactId>factory-kit</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

factory-kit/src/main/java/com/iluwatar/factorykit/App.java

@@ -0,0 +1,54 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+/**
+ * Factory-kit is a creational pattern which defines a factory of immutable content
+ * with separated builder and factory interfaces to deal with the problem of
+ * creating one of the objects specified directly in the factory-kit instance.
+ *
+ * <p>
+ * In the given example {@link WeaponFactory} represents the factory-kit, that contains
+ * four {@link Builder}s for creating new objects of
+ * the classes implementing {@link Weapon} interface.
+ * <br>Each of them can be called with {@link WeaponFactory#create(WeaponType)} method, with
+ * an input representing an instance of {@link WeaponType} that needs to
+ * be mapped explicitly with desired class type in the factory instance.
+ */
+public class App {
+  /**
+   * Program entry point.
+   *
+   * @param args @param args command line args
+   */
+  public static void main(String[] args) {
+    WeaponFactory factory = WeaponFactory.factory(builder -> {
+      builder.add(WeaponType.SWORD, Sword::new);
+      builder.add(WeaponType.AXE, Axe::new);
+      builder.add(WeaponType.SPEAR, Spear::new);
+      builder.add(WeaponType.BOW, Bow::new);
+    });
+    Weapon axe = factory.create(WeaponType.AXE);
+    System.out.println(axe);
+  }
+}

factory-kit/src/main/java/com/iluwatar/factorykit/Axe.java

@@ -0,0 +1,30 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+public class Axe implements Weapon {
+  @Override
+  public String toString() {
+    return "Axe";
+  }
+}

factory-kit/src/main/java/com/iluwatar/factorykit/Bow.java

@@ -0,0 +1,30 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+public class Bow implements Weapon {
+  @Override
+  public String toString() {
+    return "Bow";
+  }
+}

factory-kit/src/main/java/com/iluwatar/factorykit/Builder.java

@@ -0,0 +1,32 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+import java.util.function.Supplier;
+
+/**
+ * Functional interface that allows adding builder with name to the factory.
+ */
+public interface Builder {
+  void add(WeaponType name, Supplier<Weapon> supplier);
+}

factory-kit/src/main/java/com/iluwatar/factorykit/Spear.java

@@ -0,0 +1,30 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+public class Spear implements Weapon {
+  @Override
+  public String toString() {
+    return "Spear";
+  }
+}

factory-kit/src/main/java/com/iluwatar/factorykit/Sword.java

@@ -0,0 +1,30 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+public class Sword implements Weapon {
+  @Override
+  public String toString() {
+    return "Sword";
+  }
+}

factory-kit/src/main/java/com/iluwatar/factorykit/Weapon.java

@@ -0,0 +1,29 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+/**
+ * Interface representing weapon.
+ */
+public interface Weapon {
+}

factory-kit/src/main/java/com/iluwatar/factorykit/WeaponFactory.java

@@ -0,0 +1,55 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+import java.util.HashMap;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+/**
+ * Functional interface, an example of the factory-kit design pattern.
+ * <br>Instance created locally gives an opportunity to strictly define
+ * which objects types the instance of a factory will be able to create.
+ * <br>Factory is a placeholder for {@link Builder}s
+ * with {@link WeaponFactory#create(WeaponType)} method to initialize new objects.
+ */
+public interface WeaponFactory {
+
+  /**
+   * Creates an instance of the given type.
+   * @param name representing enum of an object type to be created.
+   * @return new instance of a requested class implementing {@link Weapon} interface.
+   */
+  Weapon create(WeaponType name);
+
+  /**
+   * Creates factory - placeholder for specified {@link Builder}s.
+   * @param consumer for the new builder to the factory.
+   * @return factory with specified {@link Builder}s
+   */
+  static WeaponFactory factory(Consumer<Builder> consumer) {
+    HashMap<WeaponType, Supplier<Weapon>> map = new HashMap<>();
+    consumer.accept(map::put);
+    return name -> map.get(name).get();
+  }
+}

factory-kit/src/main/java/com/iluwatar/factorykit/WeaponType.java

@@ -0,0 +1,30 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit;
+
+/**
+ * Enumerates {@link Weapon} types
+ */
+public enum WeaponType {
+  SWORD, AXE, BOW, SPEAR
+}

factory-kit/src/test/java/com/iluwatar/factorykit/app/AppTest.java

@@ -0,0 +1,36 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit.app;
+
+import com.iluwatar.factorykit.App;
+import org.junit.Test;
+
+public class AppTest {
+
+  @Test
+  public void test() {
+    String[] args = {};
+    App.main(args);
+  }
+}
+

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

@@ -0,0 +1,81 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 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.
+ */
+package com.iluwatar.factorykit.factorykit;
+
+import com.iluwatar.factorykit.*;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+
+public class FactoryKitTest {
+
+  private WeaponFactory factory;
+
+  @Before
+  public void init() {
+    factory = WeaponFactory.factory(builder -> {
+      builder.add(WeaponType.SPEAR, Spear::new);
+      builder.add(WeaponType.AXE, Axe::new);
+      builder.add(WeaponType.SWORD, Sword::new);
+    });
+  }
+
+  /**
+   * Testing {@link WeaponFactory} to produce a SPEAR asserting that the Weapon is an instance of {@link Spear}
+   */
+  @Test
+  public void testSpearWeapon() {
+    Weapon weapon = factory.create(WeaponType.SPEAR);
+    verifyWeapon(weapon, Spear.class);
+  }
+
+  /**
+   * Testing {@link WeaponFactory} to produce a AXE asserting that the Weapon is an instance of {@link Axe}
+   */
+  @Test
+  public void testAxeWeapon() {
+    Weapon weapon = factory.create(WeaponType.AXE);
+    verifyWeapon(weapon, Axe.class);
+  }
+
+
+  /**
+   * Testing {@link WeaponFactory} to produce a SWORD asserting that the Weapon is an instance of {@link Sword}
+   */
+  @Test
+  public void testWeapon() {
+    Weapon weapon = factory.create(WeaponType.SWORD);
+    verifyWeapon(weapon, Sword.class);
+  }
+
+  /**
+   * This method asserts that the weapon object that is passed is an instance of the clazz
+   *
+   * @param weapon weapon object which is to be verified
+   * @param clazz  expected class of the weapon
+   */
+  private void verifyWeapon(Weapon weapon, Class clazz) {
+    assertTrue("Weapon must be an object of: " + clazz.getName(), clazz.isInstance(weapon));
+  }
+}

factory-method/pom.xml

@@ -29,7 +29,7 @@
   <parent>
     <groupId>com.iluwatar</groupId>
     <artifactId>java-design-patterns</artifactId>
-    <version>1.10.0</version>
+    <version>1.11.0</version>
   </parent>
   <artifactId>factory-method</artifactId>
   <dependencies>

factory-method/src/main/java/com/iluwatar/factory/method/App.java

@@ -38,25 +38,40 @@ package com.iluwatar.factory.method;
  */
 public class App {
 
+  private final Blacksmith blacksmith;
+  
+  /**
+   * Creates an instance of <code>App</code> which will use <code>blacksmith</code> to manufacture 
+   * the weapons for war.
+   * <code>App</code> is unaware which concrete implementation of {@link Blacksmith} it is using.
+   * The decision of which blacksmith implementation to use may depend on configuration, or
+   * the type of rival in war.
+   * @param blacksmith a non-null implementation of blacksmith
+   */
+  public App(Blacksmith blacksmith) {
+    this.blacksmith = blacksmith;
+  }
+  
   /**
    * Program entry point
    * 
    * @param args command line args
    */
   public static void main(String[] args) {
-    Blacksmith blacksmith;
+    // Lets go to war with Orc weapons
+    App app = new App(new OrcBlacksmith());
+    app.manufactureWeapons();
+    
+    // Lets go to war with Elf weapons
+    app = new App(new ElfBlacksmith());
+    app.manufactureWeapons();
+  }
+  
+  private void manufactureWeapons() {
     Weapon weapon;
-
-    blacksmith = new OrcBlacksmith();
     weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
     System.out.println(weapon);
     weapon = blacksmith.manufactureWeapon(WeaponType.AXE);
     System.out.println(weapon);
-
-    blacksmith = new ElfBlacksmith();
-    weapon = blacksmith.manufactureWeapon(WeaponType.SHORT_SWORD);
-    System.out.println(weapon);
-    weapon = blacksmith.manufactureWeapon(WeaponType.SPEAR);
-    System.out.println(weapon);
   }
 }

factory-method/src/test/java/com/iluwatar/factory/method/FactoryMethodTest.java

@@ -93,7 +93,7 @@ public class FactoryMethodTest {
    * @param expectedWeaponType expected WeaponType of the weapon
    * @param clazz expected class of the weapon
    */
-  private void verifyWeapon(Weapon weapon, WeaponType expectedWeaponType, Class clazz) {
+  private void verifyWeapon(Weapon weapon, WeaponType expectedWeaponType, Class<?> clazz) {
     assertTrue("Weapon must be an object of: " + clazz.getName(), clazz.isInstance(weapon));
     assertEquals("Weapon must be of weaponType: " + clazz.getName(), expectedWeaponType,
         weapon.getWeaponType());