Wzorce projektowe – wzorzec Adapter

Wzorzec Adapter można zaimplementować jako Two Ways Adapter aczkolwiek jest to rzadko stosowane.

 public enum ShapeType {
    CIRCLE, RECTANGLE, TRIANGLE,RHOMBUS
} 

 public class TwoWaysAdapter implements Shape, GeometricShape {
private ShapeType shapeType;
public TwoWaysAdapter() {
    this(ShapeType.TRIANGLE);
 }
 public TwoWaysAdapter(ShapeType shapeType) {
    super();
    this.shapeType = shapeType;
}
  @Override
   public void draw() {
   switch (shapeType) {
   case CIRCLE:
   new Circle().draw();
   break;
   case RECTANGLE:
   new Rectangle().draw();
   break;
   case TRIANGLE:
   new Triangle().drawShape();
   break;
   case RHOMBUS:
   new Rhombus().drawShape();
   break;
  }
}
 @Override
 public void resize() {
 switch (shapeType) {
 case CIRCLE:
 new Circle().resize();
 break;
 case RECTANGLE:
 new Rectangle().resize();
 break;
 case TRIANGLE:
 System.out.println("Triangle can't be resized. Please create new    one with required values.");
 break;
case RHOMBUS:
 System.out.println("Rhombus can't be resized. Please create new one with required values.");
 break;
 }
}
 @Override
 public double area() {
 switch (shapeType) {
 case CIRCLE:
 case RECTANGLE:
 return 0.0d;
 case TRIANGLE:
 return new Triangle().area();
 case RHOMBUS:
 return new Rhombus().area();
 }
  return 0.0d;
}
 @Override
 public double perimeter() {
 switch (shapeType) {
 case CIRCLE:
 case RECTANGLE:
 return 0.0d;
 case TRIANGLE:
 return new Triangle().perimeter();
 case RHOMBUS:
 return new Rhombus().perimeter();
 }
 return 0.0d;
}
  @Override
   public void drawShape() {
   draw();
   }
} 

Zródła:

• https://dzone.com/articles/adapter-design-pattern-in-java
• http://java.edu.pl/inne/designPatterns/6.adapter.php