explain

[krishna prasad]

can anybody help me what is happening in the following example
class B{
protected int x;
B(){ x = 10;}
B(int a){ x = a;}
void m1(){x = 20;}
void m1(int x){this.x = x;}
}
public class A {
int x;
A(){x = 20;}
A(int x){this.x = x;}
void m1(B x){this.x = x.x++;}
public static void main(String arf[]){
A x = new A(20);
B y = new B();
System.out.println(x.x);
x.m1(y);
System.out.println(x.x);
y.m1(30);
System.out.println(y.x);
((A)x).m1(y);
System.out.println(y.x);
}
}

[bill bozeman]

Tell us what you don't understand first, so we can answer it more directly.
Also, I am going to move this to the Certification forum.
Bill

[Francisco I]

It outputs
20
10
30
31.
Don't get confused with x within a class and x as an Object.
in main() x.x refers to the variable x within class A.
y.x refers to the variable x within the class B.
if you want to understand it better, my advice is change the variables within A to xA and the ones in B to xB. Then, the ones in main() to objX and objY and you'll probably see it clearer.