Constructor

A constructor in Java is a special method that is used to initialize objects. The constructor is called when an object of a class is created. It can be used to set initial values for object attributes.

Constructors can also take parameters, which is used to initialize attributes. 

class a{

    public int a;

    public a(){

        System.out.println("We Are In Default Constructor");

    }

    public a(int a){

        this.a=a;

        System.out.println("We Are In Parameterized Constructor");

    }

}

class main{

    public static void main(String [] args)

    {

        a  obj =new a();                         //here Default Constructor calling

        a obj1=new a(3);                       //here Parameterized Constructo calling

    }

}