Constructor Overloading

Information about Constructor

• The constructor name is the same as the class name.
• The default constructor has no arguments.
• The constructor is called when the class object is created.

What is Constructor Overloading?

• Constructor overloading means having more than one constructor in the same class.
• Each constructor should have a different signature (parameters) to prevent compile-time errors.

Example

1. Default Constructor

   public Program() {
       System.out.println("This is the first constructor");
   }
   

2. Constructor with Two Arguments

   public Program(int a, int b) {
       System.out.println(a + b);
   }
   

3. Constructor with Three Arguments

   public Program(int a, int b, int c) {
       System.out.println(a + b + c);
   }
   

4. Constructor with String Arguments

   public Program(String a, String b, String c) {
       System.out.println(a + b + c);
   }
   

Calling Constructor While Creating Object

• Calling Default Constructor

  Program p = new Program();
  

  • Output: This is the first constructor
• Calling Constructor with Two Arguments

  Program p = new Program(20, 30);
  

  • Output: 50
• Calling Constructor with Three Arguments

  Program p = new Program(20, 30, 20);
  

  • Output: 70
• Calling Constructor with String Arguments

  Program p = new Program("a", "b", "c");
  

  • Output: abc

Key Points

• In constructor overloading, all constructors must have a different signature.
• The correct constructor is chosen at compile-time based on the arguments.
• An error will occur if you create constructors with the same signature.