再帮我看一段代码,马上结贴

Question

import java.applet.Applet;import java.awt.*;
import javax.swing.*;public class SimpleTab extends JFrame{
   
    JTabbedPane jtp;
    String[] pages ={" Rule1"," Rule2"," Rule3"," Rule4"," Rule5"," Rule6"};    public SimpleTab() {
      super("General Decoder Manager");
      setSize(800,600);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      Container contents = getContentPane();
      jtp = new JTabbedPane();
      JPanel pnlRule = new JPanel();
      JPanel pnlConfig = new JPanel();
      JPanel pnlRuleright = new JPanel();
      JList RuleList = new JList(pages);
      RuleList.setPreferredSize(new Dimension(150,100));
      RuleList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
      pnlRule.setLayout(new BorderLayout());
      pnlRule.add(new JScrollPane(RuleList),BorderLayout.WEST);
      
      pnlRuleright.setLayout(new GridBagLayout());
      GridBagConstraints c = new GridBagConstraints(); 
    
      JLabel lblKeyWord = new JLabel("Key Word");
      JTextField edtKeyWord = new JTextField(20);
      
      c.gridx = 0;
      c.gridy = 0;
      c.weightx = 1;
      c.fill = GridBagConstraints.HORIZONTAL;
      //((GridBagLayout)getLayout()).setConstraints(lblKeyWord,c); //这里报错
      pnlRule.add(lblKeyWord);
      
      
      c.gridx = 1;
      c.gridy = 0;
      c.weightx = 1;
      c.fill = GridBagConstraints.HORIZONTAL;
      //((GridBagLayout)getLayout()).setConstraints(edtKeyWord,c); //这里报错
      pnlRule.add(edtKeyWord);
      pnlRule.add(pnlRuleright,BorderLayout.CENTER);
    
      jtp.addTab("Rule Manager",pnlRule);
      jtp.addTab("GDM configure",pnlConfig);
      contents.add(jtp);
      setVisible(true);    }    public static void main(String[] args) {
        SimpleTab simpleTab = new SimpleTab();
    }}
报错信息为:
Exception in thread "main" java.lang.ClassCastException: java.awt.BorderLayout
at SimpleTab.<init>(SimpleTab.java:42)
at SimpleTab.main(SimpleTab.java:55)
Process exited with exit code 1.大家帮忙指点,谢谢

Answer 1

http://java.eweiter.com/java/Javachujirumenjiaocheng(3)/

Answer 2

ls,如果用extends Applet 就OK,我查过例子,但我这里用JFRAME就不行吗?

Answer 3

((GridBagLayout) pnlRuleright.getLayout()).setConstraints(lblKeyWord,c); 

Answer 4

//((GridBagLayout)pnlRuleright.getLayout()).setConstraints(lblKeyWord,c);   //这里报错 
前面要加对象,晕用JAVA做GUI,快死人了

Answer 5

//((GridBagLayout)getLayout()).setConstraints(lblKeyWord,c);   //这里报错
---------------------
getLayout()前面没有对象，那就是缺省对象this，即相当于
this.getLayout();//this就是SimpleTab的isntance
显然，你的GridBagLayout是设置到pnlRuleright的，而不是设置到this，所以this.getLayout();返回的对象就不是GridBagLayout的实例，所以强行转换就会出错。