Interface

[Dipen Javia]

Hello,

I am *really* confused what an Interface is and what Interface does. I would really appreciate if someone could explain me what an Interface is and what it does with an example if possible.

Thanx in advance

[Leo Deegan]

Hi Dipen, here's one main use for an interface:

An interface is used to declare methods without defining their behavior. The behavior is implemented in the classes that implement that interface.

Take, for example, the following interface.

public interface MathOperator {
    public double operateOn(double n1, double n2);
}

The above interface declares a method (operateOn), but does not define what the method does. The following classes provide different behavior by implementing the interface.

public class Adder implements MathOperator {
    public double operateOn(double n1, double n2) {
        return n1 + n2;
    }
}
 
public class Averager implements MathOperator {
    public double operateOn(double n1, double n2) {
        return (n1 + n2)/2.0;
    }
}

[Dipen Javia]

Hey Leo,

Thank you so much for exaplaing the use of an interface with an example. I really appreciate your help.
[ June 16, 2004: Message edited by: Dipen Javia ]