First Time problem!

Ok, Ive built some overly complex programs, and lately ive been trying to OOP more, making things neater, but ive run into my first OOP problem! Ive made a demonstration program, here it is!

Java Objects:

Code:

---

[B]Main.java[/B]
[CODE]
package vtest1;
class Main{
    public static void main(String[] args) {
      Panel2 p2 = new Panel2();
      p2.setup();
    }
}

---

Panel1.java

Code:

---

package vtest1;
public class Panel1 {
    public void intTest() {
        Panel2 p2 = new Panel2();
        int x = p2.x;
        int y = p2.y;
        [COLOR="Blue"]System.out.println(x+","+y);[/COLOR]
    }
}

---

Panel2.java

Code:

---

package vtest1;
public class Panel2 {
    int x;
    int y;
    public void setup(){
        Panel1 p1 = new Panel1();
        x = 10;
        y = 10;
        print();
        p1.intTest();
    }
    public void print(){
        [COLOR="Red"]System.out.println(x+","+y);[/COLOR]
    }
}

---

[/CODE]

The first output (Highlighted in red) prints the x and y, so it prints 10,10.
The second output (Highlighted in blue) SHOULD print the x,y (10,10) also! but it doesn't, instead it prints 0,0.

My problem is that my x,y veritable values are not being recognized in my panel1 object!? please help!

Because the instance of Panel2 (p2) in intTest() is another one than the p2 in your main method! In initTest() you instantiate a new object and invoke only the default constructor which doesnt set the x and y variables, so they have their default values (0)

So, how do i fix this?

You need to somehow pass a reference of the panel2 object to the panel1 object.

The simplest way is to modify the intTest method to

Code:

---

public class Panel1 {
    public void intTest(Panel2 p2) {
        int x = p2.x;
        int y = p2.y;
        System.out.println(x+","+y);
    }
}

---

you should then call this method like

Code:

---

p1.intTest(this);

---

if you dont understand why, please ask.

Haha, i understand the first code black modification, Its the p2 reference/deceleration. The second codeblack on the other hand, the "p1.intTest(this);" i do not understand!

Quote:

---

Originally Posted by Jcbconway

Ok, Ive built some overly complex programs, and lately ive been trying to OOP more, making things neater...

---

To be frank, your OOP example is quite complex too... Especially using two class that have almost the same name but different functionality and using two member variables with the same name (p2) doesn't help to understand the code easily.

What exactly are you trying to demonstrate with this code?

Erik

Well, the demonstration is to just show my variable reference problem.

I can never really explain the "this" keyword, so look at Using the this Keyword (The Java™ Tutorials > Learning the Java Language > Classes and Objects)