super java

//Class A is referred to as the superclass or base class.
//Class B is referred to as the subclass or derived class.

class A {
    //constructor
    public A() {
        super();
        System.out.println("in A");
    }

    public A(int n) {
        super();
        System.out.println("in A int n");
    }

}

class B extends A {
    //constructor
    public B() {
        super();
        System.out.println("in B");
    }

    public B(int n) {
        super(n);
        System.out.println("in B int n");
    }
}

class C extends A {
    //constructor
    public C() {
        super();
        System.out.println("in B");
    }

    public C(int n) {
        this(); // this will execute the default constructor `public C() {`.
        System.out.println("in B int n");
    }
}

public class _05_ThisAndSuper {
    public static void main(String[] args) {
        /* ------------------------------------------------------ */
        // without using super()
        B obj = new B(); // → "in A" \n "in B"

        B obj2 = new B(2); // → "in A" \n "in B int n"
        // Why is it calling the constructor of the parent class ?
        //The thing is, every constructor in JAVA has a super(); method even if you don't see it.
        // By default, in every constructor the first statement is super();

        // super(); means that : call the constructor of the super class (here, class A), but which one? The default one (and not the parameterized one).

        //However, if we want to call the parameterized constructor we'll  use super(n); i.e parameterized super. (see below)

        /* ------------------------------------------------------ */
        // with super(n);
        B obj4 = new B(2);
        /* Prints :

        in A int n
        in B int n

        */

        /* ------------------------------------------------------ */

        // but what is the super class of class A ?
        // by default class A is extended to Object i.e.
        // class A extends Object {..}

        /* ------------------------------------------------------ */
        // what if we want to execute both the constructors in a class ?
        // we'll use "this" keyword for that.
        C obj5 = new C(32);
        /* Prints :

        in A
        in B
        in B int n

        */
    }
}