In this tutorial you will learn about the construction overloading in Java and understand this concept with the example. In Java you can have a class with multiple constructor with different parameter. Java allows you to create a class with multiple constructor.
The multiple constructor allows you to instantiate your class by passing different values for the constructor.
We have developed an example class here which take different parameters in constructor definition. We have Rectangle class with following constructor definitions:
So, this way you can define as many constructor as you want based on your requirement.
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:
Output of the program is given below:
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
In this example you learned to define a class with multiple constructor and then use in your program.