Child objects and parent objects being passed into the same method

Question

I have a custom QuadBatch method, which as the name suggests, batches up quads to be drawn with one openGL call.

I have 2 objects, which are created as follows:

QuadBatch sprite1 = new QuadBatch();

NewSprite sprite2 = new NewSprite();

This is where QuadBatch is the parent class, and NewSprite is a subclass of it (ie, it extends QuadBatch).

I did this because NewSprite required everything in the QuadBatch class, but also some extra stuff.

If I have an animate method which takes a NewSprite object like so:

public void animate(NewSprite newSprite){

//animation code here

}

How can I use this same method but passing in a QuadBatch object? I can't just pass in a QuadBatch object as the method expects a NewSprite object.

The same question applies in reverse if the argument taken by the animate() method was a QuadBatch object. How could I pass in a NewSprite object?

Answer 1

You just have your method take the parent class as the parameter...

public void animate(QuadBatch param) {

  // animation code here

  //if you need specific method calls you could cast the parameter here to a NewSprite
  if (param instanceof NewSprite) {
      NewSprite newSprite = (NewSprite)param;
      //do NewSprite specific stuff here
  }

}

//However, hopefully you have a method like doAnimate() on QuadBatch 
//that you have overloaded in NewSprite
//and can just call it and get object specific results

public void animate(QuadBatch param) {

  param.doAnimate();

}