Types of constructor

In Java, a constructor is a special method used to initialize objects. Unlike regular methods, constructors are invoked when an instance of a class is created. They have the same name as the class and do not have a return type. Constructors are essential for setting initial values for object attributes and preparing the object for use.

Types of Constructors:

1. Default Constructor:

A default constructor is automatically provided by the Java compiler if no constructors are explicitly defined in the class. It initializes the object with default values.

public class Car {
    String model;
    int year;

    // Default Constructor
    public Car() {
        model = "Unknown";
        year = 0;
    }

    public static void main(String[] args) {
        Car car = new Car();
        System.out.println("Model: " + car.model + ", Year: " + car.year);
    }
}

2. No-Argument Constructor:

A no-argument constructor is explicitly defined by the programmer and does not take any parameters. It is similar to the default constructor but can include custom initialization code.

class Company {
  String name;

  // public constructor
  public Company() {
    name = "Programiz";
  }
}

class Main {
  public static void main(String[] args) {

    // object is created in another class
    Company obj = new Company();
    System.out.println("Company name = " + obj.name);
  }
}

output:

Company name = Programiz

3. Parameterized Constructor:

A parameterized constructor accepts arguments to initialize an object with specific values. This allows for more flexible and controlled initialization of object attributes.

public class Car {
    String model;
    int year;

    // Parameterized Constructor
    public Car(String model, int year) {
        this.model = model;
        this.year = year;
    }

    public static void main(String[] args) {
        Car car = new Car("Toyota", 2021);
        System.out.println("Model: " + car.model + ", Year: " + car.year);
    }
}