java - How to open JCombobox in a addPropertyChangeListener -

in jdatechooser, have added addpropertychangelistener detects if date chosen. if chosen, want open jcombobox. (date) string detected when select, can't open jcombobox.

here code:

datechoosercal.getdateeditor().addpropertychangelistener(new propertychangelistener() {     public void propertychange(propertychangeevent evt)      {         date = datechoosercal.getdate();          if ("date".equals(evt.getpropertyname()))          {                dates = evt.getnewvalue();             datestring = string.format("%1$td-%1$tm-%1$ty", date);               if (datestring != null)              {                 system.out.print(datestring);                 choosetimebox = new jcombobox(controllerapp.gettime());                 choosetimebox.setbounds(215, 261, 282, 22);                 add(choosetimebox);                 choosetimebox.setvisible(true);             }          }      }         }); 

well fact combo box isn't contained within displayable element primary cause of issue...

// create new instance choosetimebox = new jcombobox(controllerapp.gettime()); //  position , size, more on later... choosetimebox.setbounds(215, 261, 282, 22); // make visible...but it's visible default... choosetimebox.setvisible(true); // never add anything... 

because seem using instance field, might guess have created previous instance , have added it, in case, should updating instances model...

avoid using null layouts, pixel perfect layouts illusion within modern ui design. there many factors affect individual size of components, none of can control. swing designed work layout managers @ core, discarding these lead no end of issues , problems spend more , more time trying rectify

have @ why frowned upon use null layout in swing? , laying out components within container more details...