java - Instance of class is 'null' when action performed on netbeans GUI button -

i have program complete number of classes create complex objects, custom variables , arrays of variables. want tie functionality of these classes actionperformed() method calls on buttons , other components (such jtextpanes) within netbeans gui.

do need port code ui form class? not believe since have stepped through debugging program, checking status of variables, , should be. however, when hit break point pushing 1 of 'buttons', instance of class being used in ui form 'null'. puzzling me since referencing correct instance of class until hit button.

i new netbeans gui building explains incompetence in area.

all suggestions welcome guys.

this code associated button pressing:

private void submitdetailsbuttonmouseclicked(java.awt.event.mouseevent evt)  {     //outputtextarea.settext("get out");     dm.dhist2.framestack[dm.dhist2.frameamount].setaccomname("win");     dm.dhist2.saveandstoreframe(); } 

the 'dm' here instance of discoursemanager class (my own work) within main, here:

public static void main(string args[])  {     discoursemanager dm = new discoursemanager();      java.awt.eventqueue.invokelater(new runnable()     {          public void run()         {          new dialoguemanagerui().setvisible(true);         }     });      dm.starttransaction();     dm.rundemo();  } 

bear in mind code within ui form. declare local instance of dm @ top of form within following:

public class dialoguemanagerui extends javax.swing.jframe { public static discoursemanager dm; .... } 

the instance of class being recognised, proven when reach breakpoint, @ dm.rundemo() line. once hit button , break point hit (placed 1 on button method), says dm null. hope silly error missing, since rearranging code soul-destroying add ui demo purposes.

the easiest way fix set static dm

final discoursemanager dm = new discoursemanager();  java.awt.eventqueue.invokelater(new runnable() {      public void run()     {      dialoguemanagerui.dm = dm;      new dialoguemanagerui().setvisible(true);     } }); 

but if want cleaner way eliminating public static member,

try this

public class dialoguemanagerui extends javax.swing.jframe {   private final discoursemanager dm;  dialoguemanagerui(discoursemanager dm) {     this.dm = dm; }  ... } 

and

public static void main(string args[])  {     final discoursemanager dm = new discoursemanager();      java.awt.eventqueue.invokelater(new runnable()     {          public void run()         {          new dialoguemanagerui(dm).setvisible(true);         }     });