Omar Kooheji Omar Kooheji - 5 months ago 35
Java Question

Callback functions in Java

Is there a way to pass a call back function in a Java method?

The behavior I'm trying to mimic is a .Net Delegate being passed to a function.

I've seen people suggesting creating a separate object but that seems overkill, however I am aware that sometimes overkill is the only way to do things.

Answer

If you mean somthing like .NET anonymous delegate, I think Java's anonymous class can be used as well.

public class Main {

    public interface Visitor{
        int doJob(int a, int b);
    }


    public static void main(String[] args) {
        Visitor adder = new Visitor(){
            public int doJob(int a, int b) {
                return a + b;
            }
        };

        Visitor multiplier = new Visitor(){
            public int doJob(int a, int b) {
                return a*b;
            }
        };

        System.out.println(adder.doJob(10, 20));
        System.out.println(multiplier.doJob(10, 20));

    }
}