Two usage instances of the Java keyword instanceof

The instanceof keyword is used to determine whether the object to which a reference type variable points is an instanceof a class (or interface, abstract class, parent class).
 
For example:

public interface IObject { 

}
public class Foo implements IObject{ 

}
public class Test extends Foo{ 

}
public class MultiStateTest { 

        public static void main(String args[]){ 

                test(); 

        }
        public static void test(){ 

                IObject f=new Test(); 

                if(f instanceof java.lang.Object)System.out.println("true"); 

                if(f instanceof Foo)System.out.println("true"); 

                if(f instanceof Test)System.out.println("true"); 

                if(f instanceof IObject)System.out.println("true"); 

        } 

}

Output results:

true 

true 

true 

true

 
Also, array types can be compared using instanceof. Such as

String str[] = new String[2];

STR instanceof String[] returns true.