Thread: Is it possible to instantiate an interafce ?

I'm not exactly sure whether the answer is exactly yes or no (* see edit below), but you can instantiate an anonymous object (The Java tutorial docs call these anonymous inner classes) which implements an interface:

package com.javaprogrammingforums.domyhomework;
 
interface TheInterface
{
	public void doSomething();
}
public class InstantiateAnInterface
{
	public static void main(String[] args)
	{
		new TheInterface()
		 {
		  public void doSomething()
			{
				System.out.println("Wahey!");
			}
		 }.doSomething();
	}
}

... and of course you can write your own class that *implements* an interface


edit: helloworld922 (see below) is absolutely technically correct - the answer is 'no'. The fact that we typically always comply with a request from someone to give them an instance of MouseListener (rather than saying "actually that is impossible end of story") is no excuse for my prevarication.

You cannot directly instantiate abstract classes or interfaces, period. However, what you have there is an anonymous inner class, which happens to extend another class (in this case, it's the MouseAdapter class, which happens to be abstract).

Hi Learner,

It is impossible to instantiate an interface, but you can instantiate new objects of classes which derived from that interface. For example:

interface A { }

class B implements A { }

// WRONG: A a = new A();

// CORRECT:
A a = new B();// this is possible, since B implements A

This is something called polymorphism, that means the declared type is static, but the runtime object can be changed dynamically.

immutable objects

You can not instantiate Interface in any case. And the example is just anonymous class and it looks like you are initiating Interface.