Added the prototype pattern and its unit test

src/main/java/com/designpatterns/creational/prototype/BlackColor.java

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+package src.main.java.com.designpatterns.creational.prototype;
+
+class BlackColor extends Color {
+
+    BlackColor() {
+        this.colorName = "black";
+    }
+
+    @Override
+    public String addColor() {
+        return "Black color added";
+    }
+}

src/main/java/com/designpatterns/creational/prototype/BlueColor.java

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+package src.main.java.com.designpatterns.creational.prototype;
+
+class BlueColor extends Color {
+
+    BlueColor() {
+        this.colorName = "blue";
+    }
+
+    @Override
+    public String addColor() {
+        return "Blue color added";
+    }
+
+}
+

src/main/java/com/designpatterns/creational/prototype/Color.java

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+package src.main.java.com.designpatterns.creational.prototype;
+
+/**
+ * The prototype pattern is used when the type of objects to create is determined by a prototypical instance, which
+ * is cloned to produce new objects. <p>
+ * This pattern is used to:
+ * 1. avoid subclasses of an object creator in the client application, like the factory method pattern does.
+ * 2. avoid the inherent cost of creating a new object in the standard way (e.g., using the 'new' keyword) when it is
+ * prohibitively expensive for a given application.
+ *
+ * @see <a href="https://en.wikipedia.org/wiki/Prototype_pattern">Prototype Pattern</a>
+ */
+public abstract class Color implements Cloneable {
+
+    String colorName;
+
+    public abstract String addColor();
+
+    /**
+     * This method should be called from the client instead of writing code that invokes the "new" operator on a
+     * hard-coded class name.
+     *
+     * @return a clone for the object
+     */
+    public Object clone() {
+        Object clone = null;
+        try {
+            clone = super.clone();
+        } catch (CloneNotSupportedException e) {
+            e.printStackTrace();
+        }
+        return clone;
+    }
+}

src/main/java/com/designpatterns/creational/prototype/ColorStore.java

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+package src.main.java.com.designpatterns.creational.prototype;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ColorStore {
+    private static Map<String, Color> colorMap = new HashMap<>();
+
+    static {
+        colorMap.put("blue", new BlueColor());
+        colorMap.put("black", new BlackColor());
+        colorMap.put("red", new RedColor());
+    }
+
+    public static Color getColor(String colorName) {
+        return (Color) colorMap.get(colorName).clone();
+    }
+}

src/main/java/com/designpatterns/creational/prototype/RedColor.java

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+package src.main.java.com.designpatterns.creational.prototype;
+
+class RedColor extends Color {
+
+    RedColor() {
+        this.colorName = "red";
+    }
+
+    @Override
+    public String addColor() {
+        return "Red color added";
+    }
+}

src/test/java/com/designpatterns/creational/prototype/PrototypeTest.java

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+package src.test.java.com.designpatterns.creational.prototype;
+
+import org.junit.Assert;
+import org.junit.Test;
+import src.main.java.com.designpatterns.creational.prototype.ColorStore;
+
+public class PrototypeTest {
+    @Test
+    public void testPrototype() {
+        String testFailReason = "";
+        String testOne = ColorStore.getColor("blue").addColor();
+        if (!"Blue color added".equals(testOne)) {
+            testFailReason += "TC 1 Failed: Blue couldn't be added\n";
+        }
+        String testTwo = ColorStore.getColor("black").addColor();
+        if (!"Black color added".equals(testTwo)) {
+            testFailReason += "TC 2 Failed: Black couldn't be added\n";
+        }
+        String testThree = ColorStore.getColor("red").addColor();
+        if (!"Red color added".equals(testThree)) {
+            testFailReason += "TC 3 Failed: Red couldn't be added\n";
+        }
+        String testFour = ColorStore.getColor("blue").addColor();
+        if (!"Blue color added".equals(testFour)) {
+            testFailReason += "TC 4 Failed: Blue couldn't be added\n";
+        }
+        Assert.assertEquals(testFailReason, "", testFailReason);
+    }
+}