Merge branch 'master' into add-checkstyle-into-maven

# Conflicts:
#	pom.xml

.travis.yml

@@ -3,12 +3,18 @@ language: java
 jdk:
   - oraclejdk8
 
+env:
+  global:
+  - GH_REF: github.com/iluwatar/java-design-patterns.git
+  - secure: "LxTDuNS/rBWIvKkaEqr79ImZAe48mCdoYCF41coxNXgNoippo4GIBArknqtv+XvdkiuRZ1yGyj6pn8GU33c/yn+krddTUkVCwTbVatbalW5jhQjDbHYym/JcxaK9ZS/3JTeGcWrBgiPqHEEDhCf26vPZsXoMSeVCEORVKTp1BSg="
+
 before_install:
   - "export DISPLAY=:99.0"
   - "sh -e /etc/init.d/xvfb start"
   
 after_success:
   - mvn clean test jacoco:report coveralls:report
+  - bash update-ghpages.sh
 
 # Migration to container-based infrastructure  
 sudo: false

factory-method/index.md

@@ -4,7 +4,9 @@ title: Factory Method
 folder: factory-method
 permalink: /patterns/factory-method/
 categories: Creational
-tags: Java
+tags: 
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Define an interface for creating an object, but let subclasses

faq.md

@@ -61,3 +61,7 @@ As for performance and scalability, pools can become bottlenecks, if all the
 pooled objects are in use and more clients need them, threads will become
 blocked waiting for available object from the pool. This is not the case with
 Flyweight.
+
+### Q7: What are the differences between FluentInterface and Builder patterns? {#Q7}
+
+Fluent interfaces are sometimes confused with the Builder pattern, because they share method chaining and a fluent usage. However, fluent interfaces are not primarily used to create shared (mutable) objects, but to configure complex objects without having to respecify the target object on every property change. 

fluentinterface/etc/fluentinterface.ucls

@@ -0,0 +1,100 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" 
+  realizations="true" associations="true" dependencies="false" nesting-relationships="true">  
+  <class id="1" language="java" name="com.iluwatar.fluentinterface.App" project="fluentinterface" 
+    file="/fluentinterface/src/main/java/com/iluwatar/fluentinterface/App.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="289" y="-8"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="false" protected="false" private="false" static="false"/>      
+      <operations public="true" package="true" protected="true" private="false" static="true"/>    
+    </display>  
+  </class>  
+  <class id="2" language="java" name="com.iluwatar.fluentinterface.fluentiterable.simple.SimpleFluentIterable" 
+    project="fluentinterface" 
+    file="/fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/simple/SimpleFluentIterable.java" 
+    binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="450" y="430"/>    
+    <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="3" language="java" name="com.iluwatar.fluentinterface.fluentiterable.lazy.LazyFluentIterable" 
+    project="fluentinterface" 
+    file="/fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/lazy/LazyFluentIterable.java" 
+    binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="860" y="391"/>    
+    <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.fluentinterface.fluentiterable.FluentIterable" 
+    project="fluentinterface" 
+    file="/fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/FluentIterable.java" binary="false" 
+    corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="794" y="55"/>    
+    <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>  
+  <class id="5" language="java" name="com.iluwatar.fluentinterface.fluentiterable.lazy.DecoratingIterator" 
+    project="fluentinterface" 
+    file="/fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/lazy/DecoratingIterator.java" 
+    binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="1245" y="391"/>    
+    <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="6" language="java" name="java.lang.Iterable" project="fluentinterface" 
+    file="/opt/Softwares/Eclipses/MARS/eclipse/jre/lib/rt.jar" binary="true" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="793" y="-163"/>    
+    <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>  
+  <dependency id="7">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="2"/>  
+  </dependency>  
+  <realization id="8">    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="4"/>  
+  </realization>  
+  <dependency id="9">    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="5"/>  
+  </dependency>  
+  <generalization id="10">    
+    <end type="SOURCE" refId="4"/>    
+    <end type="TARGET" refId="6"/>  
+  </generalization>  
+  <dependency id="11">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="3"/>  
+  </dependency>  
+  <dependency id="12">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="4"/>  
+  </dependency>  
+  <realization id="13">    
+    <end type="SOURCE" refId="2"/>    
+    <end type="TARGET" refId="4"/>  
+  </realization>  
+  <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"/>    
+    <operations public="true" package="true" protected="true" private="true" static="true"/>  
+  </classifier-display>  
+  <association-display labels="true" multiplicity="true"/>
+</class-diagram>

fluentinterface/index.md

@@ -0,0 +1,42 @@
+---
+layout: pattern
+title: Fluent Interface
+folder: fluentinterface
+permalink: /patterns/fluentinterface/
+categories: Other
+tags: 
+ - Java
+ - Difficulty-Intermediate
+---
+
+**Intent:** A fluent interface provides an easy-readable, flowing interface, that often mimics a domain specific language. Using this pattern results in code that can be read nearly as human language.
+
+**Implementation:**
+
+A fluent interface can be implemented using any of
+ 
+ * Method Chaining - calling a method returns some object on which further methods can be called.
+ * Static Factory Methods and Imports
+ * Named parameters - can be simulated in Java using static factory methods.
+
+![Fluent Interface](./etc/fluentinterface.png "Fluent Interface")
+
+
+**Applicability:** Use the Fluent Interface pattern when
+
+* you provide an API that would benefit from a DSL-like usage
+* you have objects that are difficult to configure or use
+
+**Real world examples:**
+
+* [Java 8 Stream API](http://www.oracle.com/technetwork/articles/java/ma14-java-se-8-streams-2177646.html)
+* [Google Guava FluentInterable](https://github.com/google/guava/wiki/FunctionalExplained)
+* [JOOQ](http://www.jooq.org/doc/3.0/manual/getting-started/use-cases/jooq-as-a-standalone-sql-builder/)
+* [Mockito](http://mockito.org/)
+* [Java Hamcrest](http://code.google.com/p/hamcrest/wiki/Tutorial)
+
+**Credits**
+
+* [Fluent Interface - Martin Fowler](http://www.martinfowler.com/bliki/FluentInterface.html)
+* [Evolutionary architecture and emergent design: Fluent interfaces - Neal Ford](http://www.ibm.com/developerworks/library/j-eaed14/)
+* [Internal DSL](http://www.infoq.com/articles/internal-dsls-java)

fluentinterface/pom.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>java-design-patterns</artifactId>
+        <groupId>com.iluwatar</groupId>
+        <version>1.6.0</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>fluentinterface</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

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

@@ -0,0 +1,103 @@
+package com.iluwatar.fluentinterface;
+
+import com.iluwatar.fluentinterface.fluentiterable.FluentIterable;
+import com.iluwatar.fluentinterface.fluentiterable.lazy.LazyFluentIterable;
+import com.iluwatar.fluentinterface.fluentiterable.simple.SimpleFluentIterable;
+
+import java.util.*;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+import static java.lang.String.valueOf;
+
+/**
+ * Fluent interface pattern is useful when you want to provide an easy readable, flowing API. Those
+ * interfaces tend to mimic domain specific languages, so they can nearly be read as human
+ * languages.
+ * <p>
+ * In this example two implementations of a {@link FluentIterable} interface are given. The
+ * SimpleFluentIterable evaluates eagerly and would be too costly for real world applications. The
+ * LazyFluentIterable is evaluated on termination. Their usage is demonstrated with a simple number
+ * list that is filtered, transformed and collected. The result is printed afterwards.
+ * <p>
+ */
+public class App {
+
+  public static void main(String[] args) {
+
+    List<Integer> integerList = new ArrayList<>();
+    integerList.addAll(Arrays.asList(
+    		1, -61, 14, -22, 18, -87, 6, 64, -82, 26, -98, 97,
+    		45, 23, 2, -68, 45
+    ));
+    
+    prettyPrint("The initial list contains: ", integerList);
+
+    List<Integer> firstFiveNegatives =
+        SimpleFluentIterable.fromCopyOf(integerList).filter(negatives()).first(3).asList();
+    prettyPrint("The first three negative values are: ", firstFiveNegatives);
+
+
+    List<Integer> lastTwoPositives =
+        SimpleFluentIterable.fromCopyOf(integerList).filter(positives()).last(2).asList();
+    prettyPrint("The last two positive values are: ", lastTwoPositives);
+
+    SimpleFluentIterable
+        .fromCopyOf(integerList)
+        .filter(number -> number % 2 == 0)
+        .first()
+        .ifPresent(
+            evenNumber -> System.out.println(String.format("The first even number is: %d",
+                evenNumber)));
+
+
+    List<String> transformedList =
+        SimpleFluentIterable.fromCopyOf(integerList).filter(negatives()).map(transformToString())
+            .asList();
+    prettyPrint("A string-mapped list of negative numbers contains: ", transformedList);
+
+
+    List<String> lastTwoOfFirstFourStringMapped =
+        LazyFluentIterable.from(integerList).filter(positives()).first(4).last(2)
+            .map(number -> "String[" + String.valueOf(number) + "]").asList();
+    prettyPrint(
+        "The lazy list contains the last two of the first four positive numbers mapped to Strings: ",
+        lastTwoOfFirstFourStringMapped);
+
+    LazyFluentIterable
+        .from(integerList)
+        .filter(negatives())
+        .first(2)
+        .last()
+        .ifPresent(
+            lastOfFirstTwo -> System.out.println(String.format(
+                "The last of the first two negatives is: %d", lastOfFirstTwo)));
+  }
+
+  private static Function<Integer, String> transformToString() {
+    return integer -> "String[" + valueOf(integer) + "]";
+  }
+
+  private static Predicate<? super Integer> negatives() {
+    return integer -> (integer < 0);
+  }
+
+  private static Predicate<? super Integer> positives() {
+    return integer -> (integer > 0);
+  }
+
+  private static <TYPE> void prettyPrint(String prefix, Iterable<TYPE> iterable) {
+    prettyPrint(", ", prefix, ".", iterable);
+  }
+
+  private static <TYPE> void prettyPrint(String delimiter, String prefix, String suffix,
+      Iterable<TYPE> iterable) {
+    StringJoiner joiner = new StringJoiner(delimiter, prefix, ".");
+    Iterator<TYPE> iterator = iterable.iterator();
+    while (iterator.hasNext()) {
+      joiner.add(iterator.next().toString());
+    }
+
+    System.out.println(joiner);
+  }
+}

fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/FluentIterable.java

@@ -0,0 +1,89 @@
+package com.iluwatar.fluentinterface.fluentiterable;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+/**
+ * The FluentIterable is a more convenient implementation of the common iterable interface based on
+ * the fluent interface design pattern. This interface defines common operations, but doesn't aim to
+ * be complete. It was inspired by Guava's com.google.common.collect.FluentIterable.
+ * 
+ * @param <TYPE> is the class of objects the iterable contains
+ */
+public interface FluentIterable<TYPE> extends Iterable<TYPE> {
+
+  /**
+   * Filters the contents of Iterable using the given predicate, leaving only the ones which satisfy
+   * the predicate.
+   * 
+   * @param predicate the condition to test with for the filtering. If the test is negative, the
+   *        tested object is removed by the iterator.
+   * @return a filtered FluentIterable
+   */
+  FluentIterable<TYPE> filter(Predicate<? super TYPE> predicate);
+
+  /**
+   * Returns an Optional containing the first element of this iterable if present, else returns
+   * Optional.empty().
+   * 
+   * @return the first element after the iteration is evaluated
+   */
+  Optional<TYPE> first();
+
+  /**
+   * Evaluates the iteration and leaves only the count first elements.
+   * 
+   * @return the first count elements as an Iterable
+   */
+  FluentIterable<TYPE> first(int count);
+
+  /**
+   * Evaluates the iteration and returns the last element. This is a terminating operation.
+   * 
+   * @return the last element after the iteration is evaluated
+   */
+  Optional<TYPE> last();
+
+  /**
+   * Evaluates the iteration and leaves only the count last elements.
+   * 
+   * @return the last counts elements as an Iterable
+   */
+  FluentIterable<TYPE> last(int count);
+
+  /**
+   * Transforms this FluentIterable into a new one containing objects of the type NEW_TYPE.
+   * 
+   * @param function a function that transforms an instance of TYPE into an instance of NEW_TYPE
+   * @param <NEW_TYPE> the target type of the transformation
+   * @return a new FluentIterable of the new type
+   */
+  <NEW_TYPE> FluentIterable<NEW_TYPE> map(Function<? super TYPE, NEW_TYPE> function);
+
+  /**
+   * Returns the contents of this Iterable as a List.
+   * 
+   * @return a List representation of this Iterable
+   */
+  List<TYPE> asList();
+
+  /**
+   * Utility method that iterates over iterable and adds the contents to a list.
+   * 
+   * @param iterable the iterable to collect
+   * @param <TYPE> the type of the objects to iterate
+   * @return a list with all objects of the given iterator
+   */
+  static <TYPE> List<TYPE> copyToList(Iterable<TYPE> iterable) {
+    ArrayList<TYPE> copy = new ArrayList<>();
+    Iterator<TYPE> iterator = iterable.iterator();
+    while (iterator.hasNext()) {
+      copy.add(iterator.next());
+    }
+    return copy;
+  }
+}

fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/lazy/DecoratingIterator.java

@@ -0,0 +1,60 @@
+package com.iluwatar.fluentinterface.fluentiterable.lazy;
+
+import java.util.Iterator;
+
+/**
+ * This class is used to realize LazyFluentIterables. It decorates a given iterator. Does not
+ * support consecutive hasNext() calls.
+ * 
+ * @param <TYPE>
+ */
+public abstract class DecoratingIterator<TYPE> implements Iterator<TYPE> {
+
+  protected final Iterator<TYPE> fromIterator;
+
+  private TYPE next = null;
+
+  /**
+   * Creates an iterator that decorates the given iterator.
+   * 
+   * @param fromIterator
+   */
+  public DecoratingIterator(Iterator<TYPE> fromIterator) {
+    this.fromIterator = fromIterator;
+  }
+
+  /**
+   * Precomputes and saves the next element of the Iterable. null is considered as end of data.
+   * 
+   * @return true if a next element is available
+   */
+  @Override
+  public final boolean hasNext() {
+    next = computeNext();
+    return next != null;
+  }
+
+  /**
+   * Returns the next element of the Iterable.
+   * 
+   * @return the next element of the Iterable, or null if not present.
+   */
+  @Override
+  public final TYPE next() {
+    if (next == null) {
+      return fromIterator.next();
+    } else {
+      final TYPE result = next;
+      next = null;
+      return result;
+    }
+  }
+
+  /**
+   * Computes the next object of the Iterable. Can be implemented to realize custom behaviour for an
+   * iteration process. null is considered as end of data.
+   * 
+   * @return the next element of the Iterable.
+   */
+  public abstract TYPE computeNext();
+}

fluentinterface/src/main/java/com/iluwatar/fluentinterface/fluentiterable/lazy/LazyFluentIterable.java

@@ -0,0 +1,230 @@
+package com.iluwatar.fluentinterface.fluentiterable.lazy;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+import com.iluwatar.fluentinterface.fluentiterable.FluentIterable;
+
+/**
+ * This is a lazy implementation of the FluentIterable interface. It evaluates all chained
+ * operations when a terminating operation is applied.
+ * 
+ * @param <TYPE> the type of the objects the iteration is about
+ */
+public class LazyFluentIterable<TYPE> implements FluentIterable<TYPE> {
+
+  private final Iterable<TYPE> iterable;
+
+  /**
+   * This constructor creates a new LazyFluentIterable. It wraps the given iterable.
+   * 
+   * @param iterable the iterable this FluentIterable works on.
+   */
+  protected LazyFluentIterable(Iterable<TYPE> iterable) {
+    this.iterable = iterable;
+  }
+
+  /**
+   * This constructor can be used to implement anonymous subclasses of the LazyFluentIterable.
+   */
+  protected LazyFluentIterable() {
+    iterable = this;
+  }
+
+  /**
+   * Filters the contents of Iterable using the given predicate, leaving only the ones which satisfy
+   * the predicate.
+   * 
+   * @param predicate the condition to test with for the filtering. If the test is negative, the
+   *        tested object is removed by the iterator.
+   * @return a new FluentIterable object that decorates the source iterable
+   */
+  @Override
+  public FluentIterable<TYPE> filter(Predicate<? super TYPE> predicate) {
+    return new LazyFluentIterable<TYPE>() {
+      @Override
+      public Iterator<TYPE> iterator() {
+        return new DecoratingIterator<TYPE>(iterable.iterator()) {
+          @Override
+          public TYPE computeNext() {
+            while (fromIterator.hasNext()) {
+              TYPE candidate = fromIterator.next();
+              if (!predicate.test(candidate)) {
+                continue;
+              }
+              return candidate;
+            }
+
+            return null;
+          }
+        };
+      }
+    };
+  }
+
+  /**
+   * Can be used to collect objects from the iteration. Is a terminating operation.
+   * 
+   * @return an Optional containing the first object of this Iterable
+   */
+  @Override
+  public Optional<TYPE> first() {
+    Iterator<TYPE> resultIterator = first(1).iterator();
+    return resultIterator.hasNext() ? Optional.of(resultIterator.next()) : Optional.empty();
+  }
+
+  /**
+   * Can be used to collect objects from the iteration.
+   * 
+   * @param count defines the number of objects to return
+   * @return the same FluentIterable with a collection decimated to a maximum of 'count' first
+   *         objects.
+   */
+  @Override
+  public FluentIterable<TYPE> first(int count) {
+    return new LazyFluentIterable<TYPE>() {
+      @Override
+      public Iterator<TYPE> iterator() {
+        return new DecoratingIterator<TYPE>(iterable.iterator()) {
+          int currentIndex = 0;
+
+          @Override
+          public TYPE computeNext() {
+            if (currentIndex < count) {
+              if (fromIterator.hasNext()) {
+                TYPE candidate = fromIterator.next();
+                currentIndex++;
+                return candidate;
+              }
+            }
+            return null;
+          }
+        };
+      }
+    };
+  }
+
+  /**
+   * Can be used to collect objects from the iteration. Is a terminating operation.
+   * 
+   * @return an Optional containing the last object of this Iterable
+   */
+  @Override
+  public Optional<TYPE> last() {
+    Iterator<TYPE> resultIterator = last(1).iterator();
+    return resultIterator.hasNext() ? Optional.of(resultIterator.next()) : Optional.empty();
+  }
+
+  /**
+   * Can be used to collect objects from the Iterable. Is a terminating operation. This operation is
+   * memory intensive, because the contents of this Iterable are collected into a List, when the
+   * next object is requested.
+   * 
+   * @param count defines the number of objects to return
+   * @return the same FluentIterable with a collection decimated to a maximum of 'count' last
+   *         objects
+   */
+  @Override
+  public FluentIterable<TYPE> last(int count) {
+    return new LazyFluentIterable<TYPE>() {
+      @Override
+      public Iterator<TYPE> iterator() {
+        return new DecoratingIterator<TYPE>(iterable.iterator()) {
+          private int stopIndex;
+          private int totalElementsCount;
+          private List<TYPE> list;
+          private int currentIndex = 0;
+
+          @Override
+          public TYPE computeNext() {
+            initialize();
+
+            TYPE candidate = null;
+            while (currentIndex < stopIndex && fromIterator.hasNext()) {
+              currentIndex++;
+              fromIterator.next();
+            }
+            if (currentIndex >= stopIndex && fromIterator.hasNext()) {
+              candidate = fromIterator.next();
+            }
+            return candidate;
+          }
+
+          private void initialize() {
+            if (list == null) {
+              list = new ArrayList<>();
+              Iterator<TYPE> newIterator = iterable.iterator();
+              while (newIterator.hasNext()) {
+                list.add(newIterator.next());
+              }
+
+              totalElementsCount = list.size();
+              stopIndex = totalElementsCount - count;
+            }
+          }
+        };
+      }
+    };
+  }
+
+  /**
+   * Transforms this FluentIterable into a new one containing objects of the type NEW_TYPE.
+   * 
+   * @param function a function that transforms an instance of TYPE into an instance of NEW_TYPE
+   * @param <NEW_TYPE> the target type of the transformation
+   * @return a new FluentIterable of the new type
+   */
+  @Override
+  public <NEW_TYPE> FluentIterable<NEW_TYPE> map(Function<? super TYPE, NEW_TYPE> function) {
+    return new LazyFluentIterable<NEW_TYPE>() {
+      @Override
+      public Iterator<NEW_TYPE> iterator() {
+        return new DecoratingIterator<NEW_TYPE>(null) {
+          Iterator<TYPE> oldTypeIterator = iterable.iterator();
+
+          @Override
+          public NEW_TYPE computeNext() {
+            while (oldTypeIterator.hasNext()) {
+              TYPE candidate = oldTypeIterator.next();
+              return function.apply(candidate);
+            }
+            return null;
+          }
+        };
+      }
+    };
+  }
+
+  /**
+   * Collects all remaining objects of this iteration into a list.
+   * 
+   * @return a list with all remaining objects of this iteration
+   */
+  @Override
+  public List<TYPE> asList() {
+    List<TYPE> copy = FluentIterable.copyToList(iterable);
+    return copy;
+  }
+
+  @Override
+  public Iterator<TYPE> iterator() {
+    return new DecoratingIterator<TYPE>(iterable.iterator()) {
+      @Override
+      public TYPE computeNext() {
+        return fromIterator.next();
+      }
+    };
+  }
+
+  /**
+   * @return a FluentIterable from a given iterable. Calls the LazyFluentIterable constructor.
+   */
+  public static final <TYPE> FluentIterable<TYPE> from(Iterable<TYPE> iterable) {
+    return new LazyFluentIterable<>(iterable);
+  }
+
+}

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

@@ -0,0 +1,198 @@
+package com.iluwatar.fluentinterface.fluentiterable.simple;
+
+import com.iluwatar.fluentinterface.fluentiterable.FluentIterable;
+
+import java.util.*;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+/**
+ * This is a simple implementation of the FluentIterable interface. It evaluates all chained
+ * operations eagerly. This implementation would be costly to be utilized in real applications.
+ * 
+ * @param <TYPE> the type of the objects the iteration is about
+ */
+public class SimpleFluentIterable<TYPE> implements FluentIterable<TYPE> {
+
+  private final Iterable<TYPE> iterable;
+
+  /**
+   * This constructor creates a copy of a given iterable's contents.
+   * 
+   * @param iterable the iterable this interface copies to work on.
+   */
+  protected SimpleFluentIterable(Iterable<TYPE> iterable) {
+    this.iterable = iterable;
+  }
+
+  /**
+   * Filters the contents of Iterable using the given predicate, leaving only the ones which satisfy
+   * the predicate.
+   * 
+   * @param predicate the condition to test with for the filtering. If the test is negative, the
+   *        tested object is removed by the iterator.
+   * @return the same FluentIterable with a filtered collection
+   */
+  @Override
+  public final FluentIterable<TYPE> filter(Predicate<? super TYPE> predicate) {
+    Iterator<TYPE> iterator = iterator();
+    while (iterator.hasNext()) {
+      TYPE nextElement = iterator.next();
+      if (!predicate.test(nextElement)) {
+        iterator.remove();
+      }
+    }
+    return this;
+  }
+
+  /**
+   * Can be used to collect objects from the Iterable. Is a terminating operation.
+   * 
+   * @return an option of the first object of the Iterable
+   */
+  @Override
+  public final Optional<TYPE> first() {
+    Iterator<TYPE> resultIterator = first(1).iterator();
+    return resultIterator.hasNext() ? Optional.of(resultIterator.next()) : Optional.empty();
+  }
+
+  /**
+   * Can be used to collect objects from the Iterable. Is a terminating operation.
+   * 
+   * @param count defines the number of objects to return
+   * @return the same FluentIterable with a collection decimated to a maximum of 'count' first
+   *         objects.
+   */
+  @Override
+  public final FluentIterable<TYPE> first(int count) {
+    Iterator<TYPE> iterator = iterator();
+    int currentCount = 0;
+    while (iterator.hasNext()) {
+      iterator.next();
+      if (currentCount >= count) {
+        iterator.remove();
+      }
+      currentCount++;
+    }
+    return this;
+  }
+
+  /**
+   * Can be used to collect objects from the Iterable. Is a terminating operation.
+   * 
+   * @return an option of the last object of the Iterable
+   */
+  @Override
+  public final Optional<TYPE> last() {
+    List<TYPE> list = last(1).asList();
+    if (list.isEmpty()) {
+      return Optional.empty();
+    }
+    return Optional.of(list.get(0));
+  }
+
+  /**
+   * Can be used to collect objects from the Iterable. Is a terminating operation.
+   * 
+   * @param count defines the number of objects to return
+   * @return the same FluentIterable with a collection decimated to a maximum of 'count' last
+   *         objects
+   */
+  @Override
+  public final FluentIterable<TYPE> last(int count) {
+    int remainingElementsCount = getRemainingElementsCount();
+    Iterator<TYPE> iterator = iterator();
+    int currentIndex = 0;
+    while (iterator.hasNext()) {
+      iterator.next();
+      if (currentIndex < remainingElementsCount - count) {
+        iterator.remove();
+      }
+      currentIndex++;
+    }
+
+    return this;
+  }
+
+  /**
+   * Transforms this FluentIterable into a new one containing objects of the type NEW_TYPE.
+   * 
+   * @param function a function that transforms an instance of TYPE into an instance of NEW_TYPE
+   * @param <NEW_TYPE> the target type of the transformation
+   * @return a new FluentIterable of the new type
+   */
+  @Override
+  public final <NEW_TYPE> FluentIterable<NEW_TYPE> map(Function<? super TYPE, NEW_TYPE> function) {
+    List<NEW_TYPE> temporaryList = new ArrayList<>();
+    Iterator<TYPE> iterator = iterator();
+    while (iterator.hasNext()) {
+      temporaryList.add(function.apply(iterator.next()));
+    }
+    return from(temporaryList);
+  }
+
+  /**
+   * Collects all remaining objects of this Iterable into a list.
+   * 
+   * @return a list with all remaining objects of this Iterable
+   */
+  @Override
+  public List<TYPE> asList() {
+    return toList(iterable.iterator());
+  }
+
+  /**
+   * @return a FluentIterable from a given iterable. Calls the SimpleFluentIterable constructor.
+   */
+  public static final <TYPE> FluentIterable<TYPE> from(Iterable<TYPE> iterable) {
+    return new SimpleFluentIterable<>(iterable);
+  }
+
+  public static final <TYPE> FluentIterable<TYPE> fromCopyOf(Iterable<TYPE> iterable) {
+    List<TYPE> copy = FluentIterable.copyToList(iterable);
+    return new SimpleFluentIterable<>(copy);
+  }
+
+  @Override
+  public Iterator<TYPE> iterator() {
+    return iterable.iterator();
+  }
+
+  @Override
+  public void forEach(Consumer<? super TYPE> action) {
+    iterable.forEach(action);
+  }
+
+
+  @Override
+  public Spliterator<TYPE> spliterator() {
+    return iterable.spliterator();
+  }
+
+  /**
+   * @return the count of remaining objects of the current Iterable
+   */
+  public final int getRemainingElementsCount() {
+    int counter = 0;
+    Iterator<TYPE> iterator = iterator();
+    while (iterator.hasNext()) {
+      iterator.next();
+      counter++;
+    }
+    return counter;
+  }
+
+  /**
+   * Collects the remaining objects of the given iterator into a List.
+   * 
+   * @return a new List with the remaining objects.
+   */
+  public static <TYPE> List<TYPE> toList(Iterator<TYPE> iterator) {
+    List<TYPE> copy = new ArrayList<>();
+    while (iterator.hasNext()) {
+      copy.add(iterator.next());
+    }
+    return copy;
+  }
+}

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

@@ -0,0 +1,12 @@
+package com.iluwatar.fluentinterface;
+
+import org.junit.Test;
+
+public class AppTest {
+
+  @Test
+  public void test() {
+    String[] args = {};
+    App.main(args);
+  }
+}

pom.xml

@@ -73,11 +73,12 @@
 		<module>front-controller</module>
 		<module>repository</module>
 		<module>async-method-invocation</module>
-		<module>business-delegate</module>
+    	<module>business-delegate</module>
-		<module>half-sync-half-async</module>
+    	<module>half-sync-half-async</module>
 		<module>step-builder</module>
 		<module>layers</module>
 		<module>message-channel</module>
+		<module>fluentinterface</module>
 	</modules>
 
 	<dependencyManagement>

singleton/presentation/index.html

@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Circular Slides - impress.js</title>
+    <style>
+        body {
+            background-image: url(//wmh.github.io/circular-slides-generator/static/img/noise.png);
+        }
+
+        .step {
+            position: relative;
+            padding: 40px;
+            margin: 0 auto;
+            -webkit-box-sizing: border-box;
+            -moz-box-sizing: border-box;
+            -ms-box-sizing: border-box;
+            -o-box-sizing: border-box;
+            box-sizing: border-box;
+            font-family: 'PT Serif', georgia, serif;
+            font-size: 48px;
+            line-height: 1.5;
+        }
+
+        .slide {
+            display: block;
+            width: 900px;
+            height: 700px;
+            padding: 120px 60px;
+            background-color: white;
+            border: 1px solid rgba(0, 0, 0, .3);
+            border-radius: 10px;
+            box-shadow: 0 2px 6px rgba(0, 0, 0, .1);
+            color: rgb(102, 102, 102);
+            text-shadow: 0 2px 2px rgba(0, 0, 0, .1);
+            font-family: 'Open Sans', Arial, sans-serif;
+        }
+
+        .credits, .credits h2 {
+            padding-top: 0;
+        }
+    </style>
+</head>
+<body>
+<div id="impress">
+    <div class="step slide" data-x="-450" data-y="-350" data-rotate="0" data-scale="0.7832222222222222"><q>My Slides</q>
+    </div>
+    <div class="step slide" data-x="557" data-y="-349" data-rotate="0" data-scale="1"><q>Slide 1</q></div>
+    <div class="step slide" data-x="-138" data-y="607" data-rotate="72" data-scale="1"><q>Slide 2</q></div>
+    <div class="step slide" data-x="-1264" data-y="241" data-rotate="144" data-scale="1"><q>Slide 3</q></div>
+    <div class="step slide" data-x="-1264" data-y="-941" data-rotate="216" data-scale="1"><q>Slide 4</q></div>
+
+    <div class="step" data-x="0" data-y="0" data-scale="5"></div>
+</div>
+<script src="//cdnjs.cloudflare.com/ajax/libs/impress.js/0.5.3/impress.js"></script>
+</body>
+</html>

update-ghpages.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# Clone gh-pages
+git clone -b gh-pages "https://${GH_REF}" ghpagesclone
+cd ghpagesclone
+
+# Init and update submodule to latest
+git submodule update --init --recursive
+git submodule update --remote
+
+# Setup Git
+git config user.name "Travis-CI"
+git config user.email "travis@no.reply"
+
+# If there is a new version of the master branch
+if git status | grep patterns > /dev/null 2>&1
+then
+  # it should be committed
+  git add .
+  git commit -m ":sparkles: :up: Automagic Update via Travis-CI"
+  git push --quiet "https://${GH_TOKEN}:x-oauth-basic@${GH_REF}" gh-pages > /dev/null 2>&1
+fi