Please someone help me to understand the flow of this program.

Question

class A
{
B obj;

A(B obj)
{
this.obj = obj;

obj.display();
}
}

class B
{
int x = 5;

B()
{
A obj = new A(this);
}

void display()
{
System.out.println("Value of x in Class B : " + x);
}
public static void main(String[] args) {
B obj = new B();
}
}

https://code.sololearn.com/c2VZ1ZNAglnE

Answer 1

Beginning from the main method-

B obj = new B();
This creates an object of type B.

Moving to class B-

B()
{
A obj = new A(this);
}
This is called and here you create an object of type A. The 'this' keyword is a reference to the current object which was created in the main method.

Moving on to class A-

A(B obj)
{
this.obj = obj;

obj.display();
}

This is called since you created an instance of A in constructor of class B.
Here you have passed the reference of the current object to 'obj' and a B type object is initialized with the same reference to the one in the main method.

obj.display();
This will call the display method from class B and the value of 'x' is displayed.

Answer 2

Where does you haven't understood ?

Answer 3

Tushar 'obj' is an object of class B. Read my explanation 'Moving on to class A'.

Answer 4

@Franck Heuba

B()
{
A obj = new A(this);
}

this part brother...

Answer 5

@Avinesh Thank you...It helped me to understand.
But I have doubt...Isn't we are only supposed to call method from it's class object only?
But In the above program we have an Object of Class A named "obj" , and calling display method from class B. WHY?