java - cannot add dynamic jtextfields and save their values -

in previos questions asked similar questions this. in previous projects used gui builder, add jtextfield panel dynamically without builder. don't why reason cannot execute code:

public class reference {     jframe frame = new jframe();     jpanel mainpanel = new jpanel();     mainpanel main = new mainpanel();     jpanel subpanel = new jpanel();     jbutton addbutton = new jbutton();     jbutton savebutton = new jbutton();     private list<jtextfield> listtf = new arraylist<jtextfield>();     /**      * @param args command line arguments      */     public static void main(string[] args) {        new reference();     }      public reference() {         frame.add(main);         frame.setlayout(new borderlayout());         frame.setdefaultcloseoperation(jframe.exit_on_close);         frame.add(addbutton, borderlayout.east);         frame.add(savebutton, borderlayout.west);         frame.pack();         frame.setsize(500, 300);          frame.setvisible(true);         main.setlayout(new borderlayout());          main.setbackground(color.green);                          main.add(subpanel);         subpanel.setbackground(color.yellow);          addbutton.addactionlistener(new actionlistener(){                 public void actionperformed(actionevent evt) {                     main.add(new subpanel());                     main.revalidate();                 }             });           savebutton.addactionlistener(new actionlistener(){                  public void actionperformed(actionevent evt) {                     (int = 0; < main.getcomponentcount();) {                 subpanel panel = (subpanel)main.getcomponent(i);                 jtextfield firstname = panel.getfirstname();                 string text = firstname.gettext();                 system.out.println( text );   }}       });      }      private class subpanel extends jpanel {            jtextfield firstname = new jtextfield(15);      public subpanel() {              this.setlayout(new boxlayout(this, boxlayout.line_axis));             this.add(firstname);       listtf.add(firstname);         }     public jtextfield getfirstname() {     return firstname; }     }      public class mainpanel extends jpanel {     list<subpanel> subpanels = new arraylist<subpanel>();      public mainpanel()     {     }      public void addsubpanel()     {         subpanel panel = new subpanel();         add(panel);         subpanels.add(panel);     }     public subpanel getsubpanel(int index)     {         return subpanels.get(index);     }   } } 

and savebutton trying value of jtextfield, without success. in output can see jframe 2 buttons, actionlistener of addbutton , savebutton not active. cannot understand wrong.

any appreciated.

in swing, order things important, example...

frame.add(main); frame.setlayout(new borderlayout()); frame.setdefaultcloseoperation(jframe.exit_on_close); frame.add(addbutton, borderlayout.east); frame.add(savebutton, borderlayout.west); frame.pack(); frame.setsize(500, 300);  frame.setvisible(true); 

1. you add main frame
2. you set frames layout (!?)
3. you add buttons
4. you pack frame
5. you set it's size (!?)
6. you make visible

the problem here step #2. if, instead, remove step #2 (step #4 , #5 aren't great either), find window contains main...

frame.add(main); frame.setdefaultcloseoperation(jframe.exit_on_close); frame.add(addbutton, borderlayout.east); frame.add(savebutton, borderlayout.west); frame.pack(); frame.setvisible(true); 

this...

for (int = 0; < main.getcomponentcount();) {     subpanel panel = (subpanel) main.getcomponent(i); 

a bad idea of 3 reasons;

1. your loop never advance (i 0)
2. you blindly casting contents of main without knowing what's on it
3. mainpanel has list of subpanels...

you need make sure adding subpanels via addsubpanel method (and should return instance of subpanel) , provide means can access list, maybe via getter of sort. although, i'd more interested in values (ie text field text) rather subpanel ;)