Question

I have a few subclasses of Shape:

Rectangle, Circle, etc.

I also have a methods in each class like this:

class Rectangle extends Shape{
    public void isIntersecting(Circle circle){ ... }  
}

class Circle extends Shape{
    public void isIntersecting(Rectangle rectangle){ ... }  
}

These methods obviously would be repeated code. My question is, how do I avoid something like this?

Answer 1

You could implement them once (in either class or as a static method somewhere) and have all methods call that shared code.

class Rectangle extends Shape{
   public boolean isIntersecting(Circle circle){ 
      return Shapes.isIntersecting(this, circle);
   }  
} 

class Circle extends Shape{
   public boolean isIntersecting(Rectangle rectangle){
       return Shapes.isIntersecting(rectangle, this);
   }  
}

class Shapes{
    static boolean isIntersecting(Rectangle rectangle, Circle circle){
       // implementation goes here
    }
}