Java Design Patterns Tutorial - Java Design Pattern - Bridge Pattern

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Bridge pattern decouples an definition from its implementation. It is a structural pattern.

This pattern involves an interface which acts as a bridge. The bridge makes the concrete classes independent from interface implementer classes.

Both types of classes can be altered without affecting each other.

Example

interface Printer {
   public void print(int radius, int x, int y);
}/*w w w . j av a  2s.  c  o m*/
class ColorPrinter implements Printer {
   @Override
   public void print(int radius, int x, int y) {
      System.out.println("Color: " + radius +", x: " +x+", "+ y +"]");
   }
}
class BlackPrinter implements Printer {
   @Override
   public void print(int radius, int x, int y) {
      System.out.println("Black: " + radius +", x: " +x+", "+ y +"]");
   }
}
abstract class Shape {
   protected Printer print;
   protected Shape(Printer p){
      this.print = p;
   }
   public abstract void draw();  
}
class Circle extends Shape {
   private int x, y, radius;

   public Circle(int x, int y, int radius, Printer draw) {
      super(draw);
      this.x = x;  
      this.y = y;  
      this.radius = radius;
   }

   public void draw() {
      print.print(radius,x,y);
   }
}
public class Main {
   public static void main(String[] args) {
      Shape redCircle = new Circle(100,100, 10, new ColorPrinter());
      Shape blackCircle = new Circle(100,100, 10, new BlackPrinter());

      redCircle.draw();
      blackCircle.draw();
   }
}

The code above generates the following result.

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