关于Swing JTable的getColumnClass

最新推荐文章于 2025-06-28 16:55:12 发布

原创最新推荐文章于 2025-06-28 16:55:12 发布 · 5.4k 阅读

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#swing #types #string #exception #object #测试

本文介绍了一个关于Swing组件JTable的基本数据类型设置导致NullPointerException的问题及解决办法。通过将表格列类型从基本类型更改为对应的封装类，成功解决了该异常。

今天在测试如下代码时，总是会报错。

jTable0.setModel(new DefaultTableModel(new Object[][] { { "0x0", 0, }, { "1x0", 0, }, }, new String[] { "string", "int", }) { private static final long serialVersionUID = 1L; Class<?>[] types = new Class<?>[] { Object.class, int.class, }; @Override public Class<?> getColumnClass(int columnIndex) { return types[columnIndex]; } });

报错信息如下：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at javax.swing.JTable.prepareRenderer(JTable.java:5729) at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:2075) at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:1977) at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1773) at javax.swing.plaf.ComponentUI.update(ComponentUI.java:143) at javax.swing.JComponent.paintComponent(JComponent.java:763) at javax.swing.JComponent.paint(JComponent.java:1027) at javax.swing.JComponent.paintChildren(JComponent.java:864) at javax.swing.JComponent.paint(JComponent.java:1036) at javax.swing.JViewport.paint(JViewport.java:747) at javax.swing.JComponent.paintChildren(JComponent.java:864) at javax.swing.JComponent.paint(JComponent.java:1036) at javax.swing.JComponent.paintChildren(JComponent.java:864) at javax.swing.JComponent.paint(JComponent.java:1036) at javax.swing.JComponent.paintChildren(JComponent.java:864) at javax.swing.JComponent.paint(JComponent.java:1036) at javax.swing.JLayeredPane.paint(JLayeredPane.java:564) at javax.swing.JComponent.paintChildren(JComponent.java:864) at javax.swing.JComponent.paintToOffscreen(JComponent.java:5129) at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:277) at javax.swing.RepaintManager.paint(RepaintManager.java:1217) at javax.swing.JComponent.paint(JComponent.java:1013) at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21) at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60) at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97) at java.awt.Container.paint(Container.java:1780) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:814) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:714) at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:694) at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:128) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

报错信息中似乎看不出什么。

最后经过多次的测试才发现，当将JTable的某一列的类型设置为基本数据类型的时候，就会产生这个错误，而设置为对应的封装类则没有这种情况，不清楚是什么原因。

上面代码稍做改动即可测试通过：

jTable0.setModel(new DefaultTableModel(new Object[][] { { "0x0", 0, }, { "1x0", 0, }, }, new String[] { "string", "int", }) { private static final long serialVersionUID = 1L; Class<?>[] types = new Class<?>[] { Object.class, Integer.class, }; @Override public Class<?> getColumnClass(int columnIndex) { return types[columnIndex]; } });