Java instanceof Operator Example

Sponsored Links

Ad by Google

The instanceof operator also known as type comparison operator, and it's very useful to compare the type of object. It compares an object to a specified type. One can use instanceof operator to test if an object is an instance of class,sub-class or interface, just like checking of serializable interface after implementation of serializable.
In this post, I am going to show you few examples of how to use instanceof operator in your code.
Example 1:
We know that, String class by default implement the Serializable interface,lets check this.

package com.javamakeuse.poc.bd;

import java.io.Serializable;

public class InstanceOfOp {
 public static void main(String[] args) {
  String str = "implemented serializable";
  if (str instanceof Serializable) {
   System.out.println("String by default implement Serializable");
  }
 }
}

Output:
String by default implement Serializable

Example 2:

package com.javamakeuse.poc.bd;

public class InstanceOfOp {
 public static void main(String[] args) {
  Parent parent = new Parent();
  Parent child = new Child();

  System.out.println("parent is parent => " + (parent instanceof Parent));
  System.out.println("child is child => " + (child instanceof Parent));
 }
}

class Parent {

}

class Child extends Parent {

}

Output:
parent is parent => true
child is child => true

Example 3:
null is not an instance of anything, so comparison with null, it should return false.

package com.javamakeuse.poc.bd;

public class InstanceOfOp {
 public static void main(String[] args) {
  String str = null;
  System.out.println(str instanceof String);
 }
}

Output:
false

Sponsored Links