JTabbedPane NullPointerException

Saya membuat JTabbedPane di JFrame menggunakan pembuat visual netbeans. Dan membangun JPanel juga. Ketika saya menambahkan JPanel sebagai tab saya mendapat kesalahan berikut. Terkadang hal itu tidak terjadi.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at com.sun.java.swing.plaf.windows.WindowsTabbedPaneUI.paintContentBorder(WindowsTabbedPaneUI.java:145)
    at javax.swing.plaf.basic.BasicTabbedPaneUI.paint(BasicTabbedPaneUI.java:791)
    at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
    at javax.swing.JComponent.paintComponent(JComponent.java:778)
    at javax.swing.JComponent.paint(JComponent.java:1054)
    at javax.swing.JComponent.paintChildren(JComponent.java:887)
    at javax.swing.JComponent.paint(JComponent.java:1063)
    at javax.swing.JComponent.paintToOffscreen(JComponent.java:5219)
    at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1529)
    at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1452)
    at javax.swing.RepaintManager.paint(RepaintManager.java:1249)
    at javax.swing.JComponent._paintImmediately(JComponent.java:5167)
    at javax.swing.JComponent.paintImmediately(JComponent.java:4978)
    at javax.swing.RepaintManager$3.run(RepaintManager.java:808)
    at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:769)
    at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:718)
    at javax.swing.RepaintManager.access$1100(RepaintManager.java:62)
    at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1677)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

Ini adalah kode untuk menambahkan JPanel sebagai Tab.

 jTabbedPane2.addTab("Swimmer",new SwimmerPanel());

Apa kesalahannya?


java netbeans nullpointerexception swing jtabbedpane
person chamathabeysinghe    schedule 05.10.2015    source sumber
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sepertinya jTabbedPane2 masih null coba inisialisasi dan periksa   -  person soorapadman    schedule 05.10.2015
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Saat ini, pertanyaan ini harus ditutup (satu sebagai duplikat dan dua tanpa kode yang dapat dijalankan). Pertimbangkan untuk memberikan contoh yang dapat dijalankan yang menunjukkan masalah Anda. Ini bukan dump kode, tetapi contoh dari apa yang Anda lakukan yang menyoroti masalah yang Anda alami. Hal ini akan mengurangi kebingungan dan memberikan respons yang lebih baik   -  person MadProgrammer    schedule 05.10.2015
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Lihat Apa yang dimaksud dengan pelacakan tumpukan, dan bagaimana cara menggunakannya untuk men-debug kesalahan aplikasi saya? & Apa yang dimaksud dengan Pengecualian Null Pointer, dan bagaimana cara memperbaikinya?   -  person Andrew Thompson    schedule 05.10.2015

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Anda mungkin tidak menginisialisasi JTabbedPane :

JTabbedPane jTabbedPane2 = new JTabbedPane();
person sh5164    schedule 06.10.2015