java - Why does Synth keeps throwing NullPointerExceptions when trying to apply a style? -

whenever try apply style jmenu or jmenuitem (via synth) lot of nullpointerexceptions whenever hover or click jmenuitems or jmenu itself, stack trace isn't giving me useful information , doesn't point anywhere @ of source files.

i loading file correctly , does display styles (apart background colors that's aside) problem lot of exceptions while working fine, program doesn't crash.

this synth lookandfeel.xml file:

<?xml version="1.0" encoding="utf-8"?> <synth>      <style id="menubarstyle">         <state>             <color value="gray" type="background"/>         </state>     </style>     <bind style="menubarstyle" type="region" key="menubar"/>      <style id="menustyle">         <insets top="5" bottom="3" right="10" left="10"/>         <state>             <color value="red" type="background"/>         </state>     </style>     <bind style="menustyle" type="region" key="menu"/>      <style id="menuitemstyle">         <insets top="5" bottom="5" left="10" right="3"/>         <state>             <color value="green" type="background"/>         </state>     </style>     <bind style="menuitemstyle" type="region" key="menuitem"/>      <style id="menuitemacceleratorstyle">         <state>             <color value="gray" type="background"/>         </state>     </style>     <bind style="menuitemacceleratorstyle" type="region" key="menuitem"/>  </synth> 

this how load file:

 private void initui() {         try {             synthlookandfeel laf = new synthlookandfeel();             laf.load(getclass().getclassloader().getresourceasstream("lookandfeel.xml"), getclass());             uimanager.setlookandfeel(laf);         } catch (parseexception e) {             e.printstacktrace();         } catch (unsupportedlookandfeelexception e) {             e.printstacktrace();         }     } 

and stack trace (printed repeatedly whenever there interaction styled components):

exception in thread "awt-eventqueue-0" java.lang.nullpointerexception     @ sun.font.fontdesignmetrics$metricskey.init(fontdesignmetrics.java:217)     @ sun.font.fontdesignmetrics.getmetrics(fontdesignmetrics.java:286)     @ sun.swing.swingutilities2.getfontmetrics(swingutilities2.java:1113)     @ javax.swing.jcomponent.getfontmetrics(jcomponent.java:1626)     @ sun.swing.menuitemlayouthelper.reset(menuitemlayouthelper.java:125)     @ javax.swing.plaf.synth.synthmenuitemlayouthelper.<init>(synthmenuitemlayouthelper.java:119)     @ javax.swing.plaf.synth.synthgraphicsutils.paint(synthgraphicsutils.java:501)     @ javax.swing.plaf.synth.synthmenuitemui.paint(synthmenuitemui.java:281)     @ javax.swing.plaf.synth.synthmenuitemui.update(synthmenuitemui.java:245)     @ javax.swing.jcomponent.paintcomponent(jcomponent.java:780)     @ javax.swing.jcomponent.paint(jcomponent.java:1056)     @ javax.swing.jcomponent.paintchildren(jcomponent.java:889)     @ javax.swing.jcomponent.paint(jcomponent.java:1065)     @ javax.swing.jcomponent.paintchildren(jcomponent.java:889)     @ javax.swing.jcomponent.paint(jcomponent.java:1065)     @ javax.swing.jcomponent.paintchildren(jcomponent.java:889)     @ javax.swing.jcomponent.paint(jcomponent.java:1065)     @ javax.swing.jlayeredpane.paint(jlayeredpane.java:586)     @ javax.swing.jcomponent.paintchildren(jcomponent.java:889)     @ javax.swing.jcomponent.paint(jcomponent.java:1065)     @ javax.swing.jcomponent.painttooffscreen(jcomponent.java:5210)     @ javax.swing.repaintmanager$paintmanager.paintdoublebuffered(repaintmanager.java:1579)     @ javax.swing.repaintmanager$paintmanager.paint(repaintmanager.java:1502)     @ javax.swing.repaintmanager.paint(repaintmanager.java:1272)     @ javax.swing.jcomponent._paintimmediately(jcomponent.java:5158)     @ javax.swing.jcomponent.paintimmediately(jcomponent.java:4969)     @ javax.swing.repaintmanager$4.run(repaintmanager.java:831)     @ javax.swing.repaintmanager$4.run(repaintmanager.java:814)     @ java.security.accesscontroller.doprivileged(native method)     @ java.security.protectiondomain$javasecurityaccessimpl.dointersectionprivilege(protectiondomain.java:76)     @ javax.swing.repaintmanager.paintdirtyregions(repaintmanager.java:814)     @ javax.swing.repaintmanager.paintdirtyregions(repaintmanager.java:789)     @ javax.swing.repaintmanager.prepaintdirtyregions(repaintmanager.java:738)     @ javax.swing.repaintmanager.access$1200(repaintmanager.java:64)     @ javax.swing.repaintmanager$processingrunnable.run(repaintmanager.java:1732)     @ java.awt.event.invocationevent.dispatch(invocationevent.java:311)     @ java.awt.eventqueue.dispatcheventimpl(eventqueue.java:756)     @ java.awt.eventqueue.access$500(eventqueue.java:97)     @ java.awt.eventqueue$3.run(eventqueue.java:709)     @ java.awt.eventqueue$3.run(eventqueue.java:703)     @ java.security.accesscontroller.doprivileged(native method)     @ java.security.protectiondomain$javasecurityaccessimpl.dointersectionprivilege(protectiondomain.java:76)     @ java.awt.eventqueue.dispatchevent(eventqueue.java:726)     @ java.awt.eventdispatchthread.pumponeeventforfilters(eventdispatchthread.java:201)     @ java.awt.eventdispatchthread.pumpeventsforfilter(eventdispatchthread.java:116)     @ java.awt.eventdispatchthread.pumpeventsforhierarchy(eventdispatchthread.java:105)     @ java.awt.eventdispatchthread.pumpevents(eventdispatchthread.java:101)     @ java.awt.eventdispatchthread.pumpevents(eventdispatchthread.java:93)     @ java.awt.eventdispatchthread.run(eventdispatchthread.java:82) 

i suspect problem has synth rather code suppose, tried looking on internet , in java documentation , tutorials on synth couldn't find relevant.

p.s: call method before start displaying or creating swing components.

update (and highly probable answer):

i found way solve problem, question remains in tact since still haven't got explanation why problem happening have hypothesis.

solution:

apparently font style should applied elements in order xml file not show errors, bare minimum required solve issue have discovered after experimentation:

<style id="defaultelementstyle">     <font name="verdana" size="12"/> </style> <bind style="defaultelementstyle" type="region" key=".*"/> 

---

hypothesis

since:

• the nullpointerexception thrown whenever there change in state of jmenu/jmenuitems.
• the problem solved setting global font property

i can safely infer problem origin calling function tried read font property of changed states *(probably 1 of classes in stack trace). however, in case mentioned above default font states undefined in xml file (null) resulted in nullpointerexception, maybe class smart enough resort default font (which displayed) , prevented program failing , crashing. thoughts on subject highly appreciated since seems problem isn't common @ , requires further investigation.