change value in the in the creator class

[livnihai]

How do i change value in the creator class
for example:

public class A {

private int num = 0;
private B b;

public A(){
b = new B();
System.out.println(num);
}
public void changeInt(int newNum){
num = newNum;
}
public static void main(String[] args) {
A a = new A();
}
}

public class B {

public B(){
A.this.changeInt(5); <-------- Error
}

}

Error: No enclosing instance of the type A is accessible in scope

thanks

[r035198x]

Read the classes section of Sun's tutorial.
That line doesn't make any sense.

A a = new A();

creates an A.

a.changeInt(5);

changes the value.

[livnihai]

ok,
i'll explain my problem.

I've created a class that listen to event, i need that when the
event happen the main class sould know about that.
I don't want to ask over and over from the main class
The question is, how do i comunicate back from the secondery class
to the main class

thanks

[Fubarable]

You could use the Observer design pattern here. It's worked well for me in this situation.

Luck.

[livnihai]

Isn't there a direct way to do it without third party ?

[Fubarable]

Isn't there a direct way to do it without third party ?

What do you mean by "third party"? No third party is needed here. You can roll your own observer / observable interfaces (I do as I don't like the ones provided by Sun).

[livnihai]

Any help how to implement Observer pattern
maybe a simple tutorial

thanks

[RamyaSivakanth]

Go thru this article.Really ,it is simple and good.

Abhi On Java: Implementing Observer Pattern in Java

[livnihai]

How do i use observer pattern on this simple example:

[code]

public class A {

private int num = 0;
private B b;

public A(){
b = new B();
System.out.println(num);
}
public static void main(String[] args) {
A a = new A();
}
}

public class B {

private int num;

public B(){
num = 10;
}
}

I need that class A will print 10

thanks