ฉันสร้าง JTabbedPane ใน JFrame โดยใช้โปรแกรมสร้างภาพ netbeans และสร้าง JPanel ด้วย เมื่อฉันเพิ่ม JPanel นั้นเป็นแท็บ ฉันได้รับข้อผิดพลาดดังต่อไปนี้ บางครั้งมันก็ไม่เกิดขึ้น
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)
นี่คือรหัสสำหรับเพิ่ม JPanel เป็นแท็บ
jTabbedPane2.addTab("Swimmer",new SwimmerPanel());
ข้อผิดพลาดคืออะไร?
