hi,

In the main window, i have a checkbox controlling the opening of an other window where i want to put as much buttons as the value of a parameter. I decided to create a for loop to do so.

see code below :

1. import guicomponents.*;
2. GButton[] modules;
3. GWindow window;
4. GCheckbox checkbox;
5. 
   
6. int imax = 4;
7. 
   
8. color colorBg = color(150);
9. 
   
10. void setup(){
11.  
12.  size(200,200);
13.  background(colorBg);
14.  checkbox= new GCheckbox(this,"check", 10,10,10);
15. }
16. 
    
17. void draw(){
18.  
19. }
20. 
    
21. void createWindow(){
22.   window=new GWindow(this, "test", 10,10,100,100,false,JAVA2D);
23.   window.setBackground(colorBg);
24.  
25.    for(int i=0; i<imax; i++){
26.  
27.     modules[i]=new GButton(this, "buttonTest "+nf(i,2),10,10+i*12,10,10);
28.     window.add(modules[i]);
29.   }
30.  
31. }
32. void handleCheckboxEvents(GCheckbox checkbox) {
33.  
34.   createWindow();
35.  
36.  }

but i'v got this error :

#############  EXCEPTION IN EVENT HANDLER  #############
An error occured during execution of the eventhandler:
CLASS: sketch_aug21c   METHOD: handleCheckboxEvents
    Caused by java.lang.NullPointerException
    sketch_aug21c.createWindow(sketch_aug21c.java:51)
########################################################

if someone can told me why Or help me to found an other way to do the same think, i will appreciate :)