Question

Possible Duplicate:
Java/C# method representation in memory

I was wondering if i have an object in java, how are it’s instance methods stored? Does an object have a pointer to it’s instance methods?

Example:

public class MyObject {
 private int x;
 private int y;
 [..]
}

If i plan keeping a lot (A big tree of objects for example) of these MyObjects in memory, will it make a significant difference in memory terms if apart from a getter for x and for y i define an instance method calculating the sum?

I’m trying to sort out wether i should add more instance methods or doing the calculations in another class using the getters and setters.

Answer 1

The object needs memory for its attributes (NOTE: for object, the attribute stored is a pointer to the real object, which lies elsewhere in memory). No additional memory is needed for methods (code) as they are stored with the class.

IE:

public class MyClass1 {
  private int myNumber;
}

and

public class MyClass2 {
  private int myNumber;
  public int MyMethod1() {
  }
  public int MyMethod2() {
  }
  public int MyMethod3() {
  }
  ....
  public int MyMethod1000() {
  }
}

use the same memory per instance.