Facade Design Pattern

Facade pattern hides the complexities of the system and provides and interface to the client using which the client can access the system.

This type of design pattern comes under structural pattern as this pattern adds an interface to existing system to hide its complexities.

Below is an example of the Facade design pattern with Diagram and Code.

 

 

Step 1.

Create Interface Shape.

Shape.java

public interface Shape{

     void draw();   
}

Step 2.

Create concrete classes implementing interface Shape.

1. Rectangle.java

public class Rectangle implements Shape {

   @Override
   public void draw() {
      System.out.println("Rectangle::draw()");
   }
}

2. Square.java

public class Square implements Shape {

   @Override
   public void draw() {
      System.out.println("Square::draw()");
   }
}

3. Circle.java

public class Circle implements Shape {

   @Override
   public void draw() {
      System.out.println("Circle::draw()");
   }
}

Step 3. Create Facade Class

public class ShapeMaker{
   private Shape circle;
   private Shape rectangle;
   private Shape square;

  public ShapeMaker(){
     
     circle = new Circle();
     rectangle = new Rectangle();
     square = new Square();
  
  }          

   public void drawCircle(){
      circle.draw();
  }
  
  public void drawRectangle(){
    
     rectangle.draw();
  }

  public void drawSquare(){

      square.draw();
   }
}    

Step 4. Use Facade to draw various of shapes.

FacadePatternDemo.java

public class FacadePatternDemo {
   public static void main(String[] args) {
      ShapeMaker shapeMaker = new ShapeMaker();

      shapeMaker.drawCircle();
      shapeMaker.drawRectangle();
      shapeMaker.drawSquare();        
   }
}