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Constructor Overloading in Java

An example that shows the use of constructor in Java programming.

Constructor Overloading in Java


Here, you will learn more about Constructor and how constructors are overloaded in Java. This section provides you a brief introduction about the Constructor that are overloaded in the given program with complete code absolutely in running state i.e. provided for best illustration about the constructor overloading in Java.

Constructors are used to assign initial values to instance variables of the class. A default constructor with no arguments will be called automatically by the Java Virtual Machine (JVM). Constructor is always called by new operator. Constructor are declared just like as we declare methods, except that the constructor don't have any return type. Constructor can be overloaded provided they should have different arguments because JVM differentiates constructors on the basis of arguments passed in the constructor.

Whenever we assign the name of the method same as  class name. Remember this method should not have any return type. This is called as constructor overloading. 

We have made one program on a constructor overloading, after going through it the concept of constructor overloading will get more clear. In the example below we have made three overloaded constructors each having different arguments  types so that the JVM can differentiates between the various constructors.

The code of the program is given below:

public class ConstructorOverloading{
  public static void main(String args[]){
  Rectangle rectangle1=new Rectangle(2,4);
  int areaInFirstConstructor=rectangle1.first();
  System.out.println(" The area of a rectangle in 
  first constructor is :  " 
+ areaInFirstConstructor);
  Rectangle rectangle2=new Rectangle(5);
  int areaInSecondConstructor=rectangle2.second();
  System.out.println(" The area of a rectangle in 
   first constructor is :  " 
+ areaInSecondConstructor);
  Rectangle rectangle3=new Rectangle(2.0f);
  float areaInThirdConstructor=rectangle3.third();
  System.out.println(" The area of a rectangle in first 
  constructor is :  " 
+ areaInThirdConstructor);
  Rectangle rectangle4=new Rectangle(3.0f,2.0f);
  float areaInFourthConstructor=rectangle4.fourth();
  System.out.println(" The area of a rectangle in first 
  constructor is :  " 
+ areaInFourthConstructor);

class Rectangle{
  int l, b;
  float p, q;
  public Rectangle(int x, int y){
  l = x;
  b = y;
  public int first(){ 
  return(l * b);
  public Rectangle(int x){
  l = x;
  b = x;
  public int second(){
  return(l * b);
  public Rectangle(float x){
  p = x;
  q = x;
  public float third(){
  return(p * q);
  public Rectangle(float x, float y){
  p = x;
  q = y;
  public float fourth(){
  return(p * q);

Output of the program is given below:

C:\java>java ConstructorOverloading
The area of a rectangle in first constructor is : 8
The area of a rectangle in first constructor is : 25
The area of a rectangle in first constructor is : 4.0
The area of a rectangle in first constructor is : 6.0

Download this program


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Posted on: March 22, 2005

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  Reload Image
July 7, 2012

current solution for constructor overloading in java
July 13, 2012

hi sir,how can i learn java with in short time of period..thnk u sir
sunil kumar
July 30, 2012

LEARN EVERYTHING, nice concept of constructor , thanks.....
August 13, 2012

August 27, 2012
Program output

IN this program 14 error is there
A Sreepriya
October 1, 2012

Its very good example and easy to understand by the person who is very new to java
poonam singh
October 11, 2012

vry hlpful in my proct.......
July 1, 2013

what is meant by constructor overloading ?explain eith an example
July 1, 2013

what is meant by constructor overloading ?explain eith an example