Constructor In Java

Constructor

• A constructor in java is a special member that is called when an object is created
• It initializes the new object state.
• It is used to set default or user-defined values for the object's attributes
• A Constructor does not have a return type , not even void
• Constructor name should be same as class name

Type of Constructor in java

1.Default Constructor
A default constructor has no parameters.
It used to assign default values to an object
If no constructor is defined
Java provides a default constructor

class Student {

    String name;
    int age;
}

public class Main {

    public static void main(String[] args) {

        Student s = new Student();

        System.out.println(s.name);
        System.out.println(s.age);
    }
}

Output
null
0

2. Parameterized Constructor or Argument Constructor

• A constructor that has parameters is known as parameterized constructor
• If we want to initialize fields of the class with our own values,then use a parameterized constructo r

public class Object {
   static String name = "Raja";
   static int no = 90;

   String product_name;
   int age;

   public Object(String product_name,int age){
        this.product_name = product_name;
        this.age = age ;
         //System.out.println("I am IRONMAN");
        }


public static void main(String [] args){

    Object product = new Object("Akilan",22);
    Object product1 = new Object("Alagu",21);
    //product.product_name = "Akilan";
   // product1.product_name = "Alagu";
    //product.age = 22;
    //product.age = 21;
    System.out.println(product.product_name);
    System.out.println(product1.product_name);
    System.out.println(product.age);
    System.out.println(product1.age);
    //System.out.println(Object.name);
    //System.out.println(Object.no);
}
}

Output
Akilan
Alagu
22
21

Constructor overloading

• Same Constructor with different no of arguments or different type of arguments
• Static polymorphism
• Earily binding
• Complie time polymorphism