Constructor in Java

→ Constructor is a special type of method also contains collection of statements that is used to initialize objects. When an object of a class is created. It can be used to set initial values for object attributes:.

Rules for creating constructor

Constructor name must be the same as, the class name √
No explicit return type √
Access modifiers can be used in constructor declaration to control its access √
A Java constructor cannot be abstract, static, final, and synchronized

Types of Java constructors

→ There are two types of constructors in Java:

Default constructor or no-arg constructor
Parameterized constructor

1) Default Constructor in java

If you don't define a constructor in a class, then compiler automatic creates a Default Constructor for the class, it is also known as no arguments.

Example1 :

 class Student{    
     Student()
      {
        System.out.println("Student Name is :- Pradeep Kumar");
    }  
  public static void main(String args[]) {  
  Student s =new Student();  
  }  
}  

Output

Example2 :

  class Demo {
     public Demo()
     {
         System.out.println("This is a no argument constructor");
     }
     public static void main(String args[]) {
    	 new Demo();
     }
}

Output

2) Parameterized Constructor in java

→ Constructor that have parameters is known as parameterized constructor.

Example1 :

  class Student{  
       int id;
       String name;
     Student(int i, String n){
        id=i;
        name=n;        
    }  
    void show() {
            System.out.println(id+ " " +name);
          }
    public static void main(String args[]){  
     Student s = new Student(01,"RojgarBharat") ;
     s.show();
     }  
  }  

Output

Parameterized Constructor Example in java

Constructor Overloading in Java

Constructor overloading is a technique, more than one constructor with different parameter list, and each constructor performs a different task .

Example1 :

 class Student{  
       int id;
       String name;
       String course;
     Student(int i, String n){
        id=i;
        name=n;
        
    } 
  Student(int i,String n,String c){
        id=i;
        name=n;
        course=c;
        
    } 
    void show() {
            System.out.println(id+ " ," +name+ ", " +course);
          }
    public static void main(String args[]){  
     Student s = new Student(01,"Bill Gates", "MCA") ;
     s.show();
     }  
  }  

Output

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OOPs Concepts

Constructor in Java

Rules for creating constructor

Types of Java constructors

1) Default Constructor in java

2) Parameterized Constructor in java

Constructor Overloading in Java