Run time Type Identification example

In this example we shall show you how to check a type identification in run time. To check a type identification in run time we have performed the following steps:

  • We have created a class A, with two methods a1() and a2().
  • We have also created a class B that extends A that overrides the inherited method from A class and also has two methods b1() and b2().
  • We create a new A object and a new B object and put them in an A array.
  • For both fields in the array we call the a1() and a2() methods. Since B class extends A and overrides its methods, we can call them in the B object,

as described in the code snippet below.  

package com.javacodegeeks.snippets.core;

package methodoverloading;

class A {

    public void a1() {

    public void a2() {

class B extends A {

    public void a1() {

    public void a2() {

    public void b1() {

    public void b2() {

    public void b3() {

public class RunTimeTypeIdentification {

    public static void main(String[] args) {

  A[] x = {new A(), new B()};



  // Compile time: method not found in Useful:


  ((B) x[1]).b1(); // Downcast/RTTI

  //((MoreUseful) x[0]).u(); // Exception thrown

This was an example of how to check a type identification in run time in Java.

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Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
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