CODEWITHSUNDEEP
java
Narendra kumar varma
Narendra kumar varma

Reputation: 1

Is default constructor generated?

In the following program the display method is not part of Student4 constructor. So, when the method display is called using the Student4 constructor object does a default constructor invokes the display method? 

class Student4 {  
    int id;  
    String name;  

    Student4(int i,String n){  
        id = i;  
        name = n;  
    }

    void display() {
        System.out.println(id+" "+name);
    }

    public static void main(String args[]) {
        Student4 s1 = new Student4(111,"Karan");
        Student4 s2 = new Student4(222,"Aryan");
        s1.display();
        s2.display();
   }
}

Upvotes: 0

Views: 88

Answers (5)

atish shimpi
atish shimpi

Reputation: 5023

Java creates default constructor itself if no constructor defined in class but if you defined parametrized constructor you have to create default constructor 

public static void main(String args[]) {
        Student4 s1 = new Student4(111,"Karan");
        Student4 s2 = new Student4(222,"Aryan");
        s1.display();
        s2.display();

       // if you create default constructor it will give you compile time issue
       // The constructor Student4() is undefined
        Student4 s3 = new Student4();
   }

When you create any instance of class, attributes and methods are the part of your object so your object is responsible to call your method not constructor.

Upvotes: 0

JDGuide
JDGuide

Reputation: 6525

As I understand , if you are not defining any explicit constructor then the default constructor will created. Here you have already declared a parameterized constructor, so here it will not create any default constructor.

Upvotes: 0

nbro
nbro

Reputation: 15837

So, when the method display is called using the Student4 constructor object

You are not calling the display function using the Student4 constructor, but using the objects s1 and s2, that you constructed using your custom constructor.

Upvotes: 1

aurelius
aurelius

Reputation: 4076

 Student4(int i,String n){  
    id = i;  
    name = n;  
    display();
 }

now, your display method is called in your custom constructor. Cheers!

Upvotes: 0

Maroun
Maroun

Reputation: 95968

So, when the method display is called using the Student4 constructor object does a default constructor invokes the display method?

No. There's no default constructor in your class since you explicitly declared your own parameterized constructor. A default constructor is a constructor that have no parameter.

Methods are never part of a constructor. The constructor is a special method that's used to set initial values for field variables. Constructors are there to create an instance of a class, so when an object is created, Java calls the constructor first.

Upvotes: 6

Related Questions