Passing functions( methods ) as arguements.

Question

I am new to java and I need to pass a method to another method within the same class. In C++ you could create a pointer to a function and pass that pointer. Can I do something like that in Java and if so How? Thanks in advance.
Barkley

Answer 1

I am new to java and I need to pass a method to
another method within the same class. In C++ you
could create a pointer to a function and pass that
pointer. Can I do something like that in Java andif
so How? Thanks in advance.
BarkleyActually there is no reason for this. You dont have
to pass the method to call it, especially since they
are in the same class
class X
void Method1()
void Method2()
Method1();
//or
this.Method1();
I think the original poster wants to be able to either: a) specify a method to call at run-time, not at compile-time OR b) specify a function that some other piece of code (that the coder has no control over) will execute upon a given event. These are the typical uses for function pointers are used for in my experience. This allows things like API call-back functions, etc in Windows programming.
As many people have suggested, the same thing can be done in Java using interfaces (as were all the "listener" classes in the Java API). A general form of this "call-back" interface would be:
public interface CallBack
  public Object func(Object o);
The Object argument and return-type above are similar to how void pointers are used in C++ allowing user data to be passed in to and out of the function thereby letting the function implementation interpret the incoming user data and letting the caller interpret the data coming out.
Now to "pass" a pointer to a function you would pass the implementer of the CallBack interface. The only difference is tacking on the ".func(...)" when
you do the actual call-back.
public class MyCallBack implements CallBack
  public Object func(Object o)
    // put implementation here...
    return null; // return something useful here maybe?
}Now do this:
MyCallBack cb = new MyCallBack();
- pass cb anywhere...the callback function would be done like this:
cb.func(...);