Constructors__java:

#programming #java

constructor:

constructors play an important role in object creation.
Its main job is to initialize the object.
This process happens automatically when we use the "new" keyword to create an object.

Characteristics of Constructors:

Same name as the class
No return type
Used to Set Initial Values for Object Attributes

Why Do We Need Constructors in Java:

It ensures that an object is properly initialized before use

Types of Constructors in Java:

There are three types of constructor in java.

1)Default Constructor
2)No Argument constructor
3)Parameterized constructor

1)Default Constructor:

if you do not create any constructor in the class.
Java provides a default constructor that initializes the object.

Example:
Default Constructor (A Class Without Any Constructor)

public class Main {
  int num1;
  int num2;

  public static void main(String[] args) {


    Main obj = new Main();


    System.out.println("num1 : " + obj.num1);
    System.out.println("num2 : " + obj.num2);
  }
}
Output

num1 : 0
num2 : 0

2)No-Args (No Argument) Constructor:

constructor that does not accept any parameters.
It is used to initialize an object with default values

Key characteristics of a no-argument constructor:

No parameters: Its method signature does not include any arguments within the parentheses.
Same name as the class: Like all constructors, its name must exactly match the name of the class it belongs to.
No return type: Constructors, including no-argument constructors, do not have a return type, not even void.

3)Parameterized Constructor:

A constructor with one or more arguments is called a parameterized constructor.
you will need a constructor that accepts one or more parameters.
Just declare them inside the parentheses after the constructor's name.

public class Main {
  int num1;
  int num2;

  // Creating parameterized constructor 
  Main(int a, int b) {
    num1 = a;
    num2 = b;
  }

  public static void main(String[] args) {

    Main obj = new Main(10, 20);
    Main obj = new Main(100, 200);

    // Printing the objects values
    System.out.println("obj");
    System.out.println("num1 : " + obj.num1);
    System.out.println("num2 : " + obj.num2);

    System.out.println("obj");
    System.out.println("num1 : " + obj.num1);
    System.out.println("num2 : " + obj.num2);
  }
}

Arguments: