issue #333 factory kit pattern introduced

factory-kit/index.md

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+---
+layout: pattern
+title: Factory Kit
+folder: factory-kit
+permalink: /patterns/factory-kit/
+categories: Creational
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Functional
+---
+
+## Also known as
+Virtual Constructor
+
+## Intent
+Define factory of immutable content with separated builder and factory interfaces.
+
+![alt text](./etc/factory-kit_1.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 custom builder instead of global one
+* a class wants its subclasses to specify the objects it creates
+* classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate
+
+## Credits
+
+* [Design Pattern Reloaded by Remi Forax: ](https://www.youtube.com/watch?v=-k2X7guaArU)

factory-kit/pom.xml

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+<?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>1.10.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <artifactId>factory-kit</artifactId>
+
+
+</project>

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

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+package com.iluwatar.factorykit;
+
+public class App {
+
+    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

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+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

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+package com.iluwatar.factorykit;
+
+/**
+ * Created by crossy on 2016-01-16.
+ */
+public class Bow implements Weapon {
+}

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

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+package com.iluwatar.factorykit;
+
+import java.util.function.Supplier;
+
+public interface Builder {
+    void add(WeaponType name, Supplier<Weapon> supplier);
+}

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

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+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

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+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

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+package com.iluwatar.factorykit;
+
+public interface Weapon {
+}

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

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+package com.iluwatar.factorykit;
+
+import java.util.HashMap;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+public interface WeaponFactory {
+
+    Weapon create(WeaponType name);
+
+    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

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+package com.iluwatar.factorykit;
+
+/**
+ * Created by crossy on 2016-01-16.
+ */
+public enum WeaponType {
+    SWORD, AXE, BOW, SPEAR
+}

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

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+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

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+package com.iluwatar.factorykit.factorykit;
+
+import com.iluwatar.factorykit.*;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Created by crossy on 2016-01-16.
+ */
+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));
+    }
+}