Merge pull request #307 from moksnow/issue297

resolving issue 297, create example for java bridge design pattern

Structural/Bridge/java/BridgeDemo.java

@@ -1,10 +1,16 @@
 
 /**
  * Created by trustgeek on 10/17/2017 {11:33 PM}.
+ * Just like Adapter pattern, bridge design pattern is one of the Structural design pattern.
+ * According to GoF bridge design pattern is:
+ * Decouple an abstraction from its implementation so that the two can vary independently
  */
 public class BridgeDemo {
     public static void main(String[] args) {
+        Shape tri = new Triangle(new RedColor());
+        tri.applyColor();
 
-
+        Shape pent = new Pentagon(new GreenColor());
+        pent.applyColor();
     }
 }

Structural/Bridge/java/Color.java

@@ -0,0 +1,3 @@
+public interface Color {
+    public void applyColor();
+}

Structural/Bridge/java/GreenColor.java

@@ -0,0 +1,6 @@
+public class GreenColor implements Color{
+
+    public void applyColor(){
+        System.out.println("green.");
+    }
+}

Structural/Bridge/java/Pentagon.java

@@ -0,0 +1,13 @@
+public class Pentagon extends Shape{
+
+    Pentagon(Color c) {
+        super(c);
+    }
+
+    @Override
+    public void applyColor() {
+        System.out.print("Pentagon filled with color ");
+        color.applyColor();
+    }
+
+}

Structural/Bridge/java/RedColor.java

@@ -0,0 +1,6 @@
+public class RedColor implements Color{
+
+    public void applyColor(){
+        System.out.println("red.");
+    }
+}

Structural/Bridge/java/Shape.java

@@ -0,0 +1,11 @@
+public abstract class Shape {
+    //Composition - implementor
+    Color color;
+
+    //constructor with implementor as input argument
+    Shape(Color c) {
+        this.color = c;
+    }
+
+    abstract public void applyColor();
+}

Structural/Bridge/java/Triangle.java

@@ -0,0 +1,13 @@
+public class Triangle extends Shape{
+
+    Triangle(Color c) {
+        super(c);
+    }
+
+    @Override
+    public void applyColor() {
+        System.out.print("Triangle filled with color ");
+        color.applyColor();
+    }
+
+}