问题描述
我的代码如下：JTabbedDemo.javaimport javax.swing.*;import java.awt.*;public class JTabbedDemo{public static void main(String[] args) throws Exception{//显示外观风格UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());JFrame jframe=new JFrame("奖金状况");jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);jframe.setVisible(true);JTabbedPane tp=new JTabbedPane();//创建一个选项卡容器，将之添加到顶层容器内jframe.setContentPane(tp);JPanel panel1=new JPanel();JPanel panel2=new JPanel();JPanel panel3=new JPanel();JPanel panel4=new JPanel();JPanel panel5=new JPanel();//添加选项卡容器，并且设置其中每个选项卡的标签以及其是否可启用。tp.addTab("panel1",panel1);tp.setEnabledAt(0,true);tp.setTitleAt(0,"个人收入状况");tp.addTab("panel2",panel2);tp.setEnabledAt(1,true);tp.setTitleAt(1,"工资");tp.addTab("panel2",panel3);tp.setEnabledAt(2,true);tp.setTitleAt(2,"奖金");tp.addTab("panel3",panel4);tp.setEnabledAt(3,true);tp.setTitleAt(3,"津贴");tp.addTab("panel4",panel5);tp.setEnabledAt(4,true);tp.setTitleAt(4,"社保");//设置其大小以及其选项卡的位置方向tp.setPreferredSize(new Dimension(800,600));tp.setTabPlacement(JTabbedPane.TOP);//设置选项卡在容器内的显示形式tp.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);jframe.pack();//创建8个标签组件，将5个中间窗口设置为流布局，并且将标签组件分别放入到其中JLabel l1=new JLabel("工资状况");JLabel l2=new JLabel("3000元/月");JLabel l3=new JLabel("奖金状况");JLabel l4=new JLabel("1500元/月");JLabel l5=new JLabel("津贴状况");JLabel l6=new JLabel("500元/月");JLabel l7=new JLabel("社保状况");JLabel l8=new JLabel("200元/月");panel2.setLayout(new FlowLayout());panel3.setLayout(new FlowLayout());panel4.setLayout(new FlowLayout());panel5.setLayout(new FlowLayout());panel2.add(l1);panel2.add(l2);panel3.add(l3);panel3.add(l4);panel4.add(l5);panel4.add(l6);panel5.add(l7);panel5.add(l8);jframe.pack();}}错误信息如下：Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at javax.swing.plaf.basic.BasicTabbedPaneUI.calculateTabWidth(Unknown Source) at javax.swing.plaf.basic.BasicTabbedPaneUI$TabbedPaneLayout.calculateTabRects(Unknown Source) at javax.swing.plaf.basic.BasicTabbedPaneUI$TabbedPaneLayout.calculateLayoutInfo(Unknown Source) at javax.swing.plaf.basic.BasicTabbedPaneUI$TabbedPaneLayout.layoutContainer(Unknown Source) at java.awt.Container.layout(Unknown Source) at java.awt.Container.doLayout(Unknown Source) at java.awt.Container.validateTree(Unknown Source) at java.awt.Container.validateTree(Unknown Source) at java.awt.Container.validateTree(Unknown Source) at java.awt.Container.validate(Unknown Source) at javax.swing.RepaintManager.validateInvalidComponents(Unknown Source) at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source) at java.awt.event.InvocationEvent.dispatch(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$000(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)
解决方案
tp.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);这句话有问题，你注释掉就没异常了，我对swing不是很了解，应该是你这种写法有问题，你看看吧，希望对你有帮助