Instanceof Operator

Instanceof Operator is important for writing the condition to check if a particular variable reference is of specific type / class. In short it is type checking condition. This operator returns true or false depends on the condition output. It always return false if you compare null value with any class. Lets look at an simple example that demonstrates the use of instanceof operator.

Employee.java

[code lang=”java”]
package javabeat.net.core;

public class Employee {}
[/code]

Manager.java

[code lang=”java”]
package javabeat.net.core;

public class Manager extends Employee{}
[/code]

InstanceOfDemo.java

[code lang=”java”]
package javabeat.net.core;

public class InstanceOfDemo {
public static void main (String args[]){
Employee employee = new Employee();
Manager manager = new Manager();
Employee employeeNull = null;

//Checking for same object
if (employee instanceof Employee){
System.out.println("Employee is instance of Employee");
}else{
System.out.println("Employee is not instance of Employee");
}

//Checking for child object to parent object
if (manager instanceof Employee){
System.out.println("Manager is instance of Employee");
}else{
System.out.println("Manager is not instance of Employee");
}

//Checking for parent object to child object
if (employee instanceof Manager){
System.out.println("Employee is instance of Manager");
}else{
System.out.println("Employee is not instance of Manager");
}
//Checking for null value to Employee object
if (employeeNull instanceof Employee){
System.out.println("null is instance of Employee");
}else{
System.out.println("null is not instance of Employee");
}

}
}
[/code]