我有一个Jtable，我正在通过比较同一表中另一个单元格的值来更改表单元格的值。我正在使用PrepareRenderer方法来更改单元格背景颜色。如果我只是将单元格值与任何字符串进行比较，或者通过使用Float解析值，则效果很好。但是，当我将其与另一个单元格值进行比较时，我得到了NullPointerException。这是代码。
@Override
public Component prepareRenderer(TableCellRenderer renderer, int rowIndex,int columnIndex) {
Component component = super.prepareRenderer(renderer, rowIndex, columnIndex);
Object value = getModel().getValueAt(rowIndex,columnIndex);
if(columnIndex == 11) {
i2 = String.valueOf(value);
}
if(columnIndex == 8){
i = String.valueOf(value);
if(i.length() != 0 ){
if(Float.parseFloat(i) < Float.parseFloat(i2)){
System.out.println(Float.parseFloat(i2));
component.setBackground(Color.GREEN);
}
}
}
else{
component.setBackground(Color.WHITE);
}
return component;
}
}
这是例外
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1838)
at sun.misc.FloatingDecimal.parseFloat(FloatingDecimal.java:122)
at java.lang.Float.parseFloat(Float.java:451)
at marutisuzuki.MainScreen$1.prepareRenderer(MainScreen.java:200)
at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:2114)
at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:2016)
at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1812)
at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
at javax.swing.JComponent.paintComponent(JComponent.java:780)
at javax.swing.JComponent.paint(JComponent.java:1056)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paint(JComponent.java:1065)
at javax.swing.JViewport.paint(JViewport.java:728)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paint(JComponent.java:1065)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paint(JComponent.java:1065)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paint(JComponent.java:1065)
at javax.swing.JLayeredPane.paint(JLayeredPane.java:586)
at javax.swing.JComponent.paintChildren(JComponent.java:889)
at javax.swing.JComponent.paint(JComponent.java:1065)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5210)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1579)
at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1502)
at javax.swing.RepaintManager.paint(RepaintManager.java:1272)
at javax.swing.JComponent._paintImmediately(JComponent.java:5158)
at javax.swing.JComponent.paintImmediately(JComponent.java:4969)
at javax.swing.RepaintManager$4.run(RepaintManager.java:831)
at javax.swing.RepaintManager$4.run(RepaintManager.java:814)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:814)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:789)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:738)
at javax.swing.RepaintManager.access$1200(RepaintManager.java:64)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1732)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
我也很愿意知道是否还有更好的方法可以完成这项任务。