Using instanceof operator

[jose chiramal]

interface Face { }

class Bar implements Face { }

class Foo extends Bar { }

Results when using the instanceof operator :

Foo [] instanceof (Foo , Bar , Face ) --- False

Foo[1] instanceof (Foo, Bar , Face , Object ) --- True

Can some one please explain the above ?

[Prithvi Sehgal]

Hello,

   
Foo[1] instanceof (Foo, Bar , Face , Object )

It is because, any Foo object is an instance of Foo.
Foo is an instance of Bar, because Foo extends Bar.
Foo is an instance of Face because Class Bar implements Face and Bar is a direct super-class of Foo, so Foo is an instance of Face as well.
Any class in Java is an instance of Object.

Hope this helps,

[John Mercier]

Also, Foo[] is an Array not a Foo.

[Prithvi Sehgal]

Jose,

Additionally, when you ask some question, please separate it from comments. Else hard time to understand your question.

Please check this out

  

interface Face{
	
}

class Bar implements Face{
	
}



public class Foo extends Bar{
	
	public static void main(String[] args) {
		
		Foo[] foo = new Foo[3];
		
		foo[0] = new Foo();
		foo[1] = new Foo();
		foo[2] = new Foo();
		
		if(foo instanceof Object){
			System.out.println("foo is an array");
		}
		  
		
		if(foo[1] instanceof Foo){
			System.out.println("foo[1] is an instance of foo");
		}
		if(foo[1] instanceof Bar){
			System.out.println("foo[1] is an instance of Bar");
		}
		if(foo[1] instanceof Face){
			System.out.println("foo[1] is an instance of Face");
		}
		if(foo[1] instanceof Object){
			System.out.println("foo[1] is an instance of Object");
		}
		
		
		
		
	}

}

Foo[] is an array and an array is only an instance of Object.
Foo[1] is talking about a specific object.

Hope this will help you clear your doubt.

Happy Preparation,

[Anup Om]

Foo [] instanceof (Foo , Bar , Face ) --- False

This will cause compilation error(if written as Java code) as Foo or Bar or Face isn't supertype of Foo[]. (i.e they don't fall under same hierarchy).

[jose chiramal]

Thanks all for responding.

[sumit kothalikar]

It is because we have made Foo[] as an array object