Improving effiency on following piece of code?

Question

Hello
I was wondering is there a way in which i can improve the effiency on the following piece of code:
public void addShapes(int x, int y, shape s){
          if(s instanceof circle){
          circle d = new circle();
          d.setX(x);
          d.setY(y);
          shapes.add(d);
          else if(s instanceof square){
               square d = new sqaure();
               d.setX(x);
               d.setY(y);
               shapes.add(d);
          else if(s instanceof triangle){
               triangle d = new triangle();
               d.setX(x);
               d.setY(y);
               shapes.add(d);
     }What the above code does is take in a shape and adds it to the arraylist of shapes which stores all shapes of all kinds such as circle, square, triangle etc...
circle, sqaure and triangle all inheret abstract class shape therefore it checks the shape being passed in to see what kind of shape it is.
Is there a better improved way of writing above code as that code is the only way i can think of to write it. It has many if ..else statements and bound to be more when i decide to add in more shapes.
Im thinking surely there is a better efficient way of writing and also reduced method length.
regards

Answer 1

mpdan wrote:
I'll chime in and ask a question.
"...returned a copy of a "shape" object..."
...(...shape s)
shape d = s.copy();
}So does copy() return a new instance or another reference to shape s?
If it returns a reference, why couldn't the OP just use shape s? If s.copy is implemented as return this, then it's the same as just getting rid of the copy method and using the original reference.
One would expect, however, that copy creates a new instance of the same kind of shape, copies the instance members from the original, and returns a reference to that new instance.
Of course, if a particular shape implementation happened to be immutable, then returning this would be perfectly acceptable, and the caller could always just call copy() without worrying about the details.
Pardon if my question is silly.Not silly. Just typical of someone without a lot of experience coming to grips with the ideas of references and objects.
Edit: I supposed the question should say "So +should+..."What it should do entirely depends on the requirements in the context in which it's being used. There's no one answer.