Constructors

Lecture 63:-  Constructors

Constructors are special methods in Java that are used to initialize the state of an object when it is created. They have the same name as the class and do not have a return type, not even void. Constructors are automatically called when you create an object using the new keyword. They help ensure that the object is properly initialized before any other operations are performed on it.

There are two main types of constructors in Java:

1. Default Constructor: If you don't explicitly define any constructors in your class, Java provides a default constructor with no arguments. It initializes the instance variables of the object with their default values (0, null, false, etc.) and is called automatically when an object is created without explicitly calling a constructor.

   Example of a default constructor:

   javaCopy code
   public class MyClass {
       // Default constructor (automatically provided if no constructors are defined)
   }
   

2. Parameterized Constructor: A parameterized constructor is a constructor that takes one or more parameters (arguments) to initialize the instance variables of the object with specific values. It allows you to provide initial values to the object's state at the time of creation.

   Example of a parameterized constructor:

   javaCopy code
   public class Person {
       String name;
       int age;
   
       // Parameterized constructor
       public Person(String name, int age) {
           this.name = name;
           this.age = age;
       }
   }
   

In the example above, the Person class has a parameterized constructor that takes two arguments (name and age) to initialize the instance variables. When you create a Person object using this constructor, you need to provide values for name and age.

Here's how you create objects using constructors:

javaCopy code
MyClass object1 = new MyClass(); // Calls the default constructor
Person person1 = new Person("John", 30); // Calls the parameterized constructor

Constructors are essential for setting up the initial state of objects and ensuring that they are in a valid and usable state before being used. By providing constructors, you can enforce certain rules and requirements for the creation of objects of your class.

Disclaimer:-

Under Section 107 of the copyright act 1976, allowance is made for fair use for purposes such as criticism, comment, news reporting, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational, or personal use tips the balance in favor of fair use.