Comments on: When can an object reference be cast to a Java interface reference?

By: chandana

chandana — Wed, 13 Jan 2010 15:12:13 +0000

Sample s= new Sample(){
// code
};
It doesnt mean that we are creating an Object for Sample Interface…
It means that an object is creating for the class implementing that Sample interface…

By: macfusion

macfusion — Thu, 17 Dec 2009 05:42:34 +0000

About chandana’s code,(Sample s = new Sample()) i thought you can’t create an instance of an interface since it has no constructor and creating an instance calls the default constructor.Please advice…great site by the way

By: Joe

Joe — Wed, 11 Nov 2009 16:07:11 +0000

Wow! Thats an excellent example Chandana. Thanks for your contribution.

By: chandana

chandana — Wed, 11 Nov 2009 14:15:30 +0000

Using anonymous Inner class concept we can create an object for an interface…..

Here is a sample code

interface Sample {
public void method();
}

class Outer {
Sample s = new Sample() {
public void method() {
System.out.println(“Inner class”);
}
};
}

public class Example {
public static void main(String args[]) {
Outer o = new Outer();
o.s.method();
}
}

Output: Inner class

By: Joe

Joe — Thu, 05 Nov 2009 02:32:42 +0000

Thanks for the nice sample source code Abhishek.

By: Abhishek Khandelwal

Abhishek Khandelwal — Tue, 03 Nov 2009 16:10:13 +0000

In other words….An interface reference can point to any object of a class that implements this interface i.e. see the example below:

interface Foo{
void display();
}

public class TestFoo implements Foo{

void display(){
System.out.println(“Hello World”);
}

public static void main(String[] args){
Foo foo = new TestFoo();
foo.display();
}

}