A Complete Guide to Java Programming/

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InstanceOf Operators

InstanceOf Operators

Learn about the instanceOf operator with the help of an example in this lesson.

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These operators check whether an object is an instance of a class or a subclass. If a class implements an interface, that can also be checked.

Coding example: 53

Let us see the following example to understand how it works:

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/*
You can use the instanceof operator to test if an object is an instance of a class,
an instance of a subclass, or an instance of a class that implements a particular interface
*/
interface PlaceTheOrder{
    public void place();
}
class ParentClass implements PlaceTheOrder{
    public void place(){
        System.out.println("Placing the order.");
    }
}
class ChildClass extends ParentClass{
}
public class ExampleFiftyThree {
    public static void main(String[] args) {
        ParentClass parent = new ParentClass();
        ChildClass child = new ChildClass();
        /*
        The following two questions will have answers true
        */
        System.out.println("Is parent instance of ParentClass? : " + (parent instanceof ParentClass));
        System.out.println("Is parent instance of interface PlaceTheOrder? : " + (parent instanceof PlaceTheOrder));
        //it is false
        System.out.println("Is parent instance of ChildClass? : " + (parent instanceof ChildClass));
        /*
        The following answers will be true, because ChildClass is a subclass of ParentClass
        */
        System.out.println("Is child instance of ChildClass? : " + (child instanceof ChildClass));
        System.out.println("Is child instance of ParentClass? : " + (child instanceof ParentClass));
        System.out.println("Is child instance of interface PlaceTheOrder? : " + (child instanceof PlaceTheOrder));
    }
}

Code explanation

As you see in the above code, there are two classes and one interface. One is the parent class, and one is the child class. The ...

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