Constructors - OOP

Java Default Constructor Example

public class Test1 {

public Test1() {
System.out.println("Inside default constructor...");
}

public static void main(String a[]) {
Test1 mdc = new Test1();
}
}


Parametarized Constructor

public class Test1 {

private String name;
   
   public Test1(String str){
       this.name = str;
       System.out.println("Inside parameterized constructor.");
       System.out.println("The parameter value is: "+str);
   }
 
   public static void main(String a[]){
    Test1 mpc = new Test1("ACH");
   }

}

Inside parameterized constructor.

The parameter value is: ACH

Constructor Overloading

public class Test1 {

private String name;

     

public Test1(){

       System.out.println("Inside default constructor");

   }

   public Test1(int i){

       System.out.println("Inside single parameter constructor with int value");

   }

   public Test1(String str){

       System.out.println("Inside single parameter constructor with String object");

   }

   public Test1(int i, int j){

       System.out.println("Inside double parameter constructor");

   }

    

   public static void main(String a[]){

    Test1 t1 = new Test1();

    Test1 t2 = new Test1(10);

    Test1 t3 = new Test1(10,20);

    Test1 t4 = new Test1("str");

   }

}

Inside default constructor

Inside single parameter constructor with int value

Inside double parameter constructor

Inside single parameter constructor with String object

Constructor Chaining Sample Code

public MyChaining(){

        System.out.println("In default constructor...");

    }

    public MyChaining(int i){

        this();

        System.out.println("In single parameter constructor...");

    }

    public MyChaining(int i,int j){

        this(j);

        System.out.println("In double parameter constructor...");

    }

     

    public static void main(String a[]){

        MyChaining ch = new MyChaining(10,20);

    }

In default constructor... 

In single parameter constructor... 

In double parameter constructor...