Re: Query regarding java Multiple Inheritance

"John B. Matthews" <nospam@nospam.invalid>
Fri, 27 Nov 2009 00:45:03 -0500
In article
 Amit Jain <> wrote:

I am new to Java and need your views for my query.

What will be the solution for implementint two Interface in a single
class A if these interfaces I1 and I2 are written as mentioned below:
interface I1{
void method ();
long square(long i);

interface I2{
String method();
long squareRoot(long i);

class A implements I1, I2{
void method(){
System.out.println("--- Hi ----");
// implementation of square() and squareRoot() method

Above implementation of interface in class A will never complies
because of "void method();" declared in both I1 and I2. And we want
the implementation of I1 and I2 in class A only. How can we acheive
this in such situations.

If the two methods named "method" are actually the same, derive A from
an abstract class that implements I1 & I2. See "When an Abstract Class
Implements an Interface":


For example,

public class AbstractInterface {

    public static void main(String[] args) {
        A a = new A();

    interface I1 {
        long square(long i);

    interface I2 {
        long cube(long i);

    private static abstract class X implements I1, I2 {
        public String method() {
            return "Hi!";

    private static class A extends X {

        public long square(long i) { return i * i; }

        public long cube(long i) { return i * i * i; }

John B. Matthews
trashgod at gmail dot com

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