Re: Query regarding java Multiple Inheritance

From:
"John B. Matthews" <nospam@nospam.invalid>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 27 Nov 2009 00:45:03 -0500
Message-ID:
<nospam-24433C.00450327112009@news.aioe.org>
In article
<b66dd337-12b5-40e5-be01-9a52d159ec78@g1g2000pra.googlegroups.com>,
 Amit Jain <amitatgroups@gmail.com> 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":

<http://java.sun.com/docs/books/tutorial/java/IandI/abstract.html>

For example,

public class AbstractInterface {

    public static void main(String[] args) {
        A a = new A();
        System.out.println(a.method());
        System.out.println(a.square(2));
        System.out.println(a.cube(2));
    }

    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 {

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

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

--
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>

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