这样写那里不对

Question

getContentPane().add(jTabbedPane1);把这句话换成add(JTabbedPanel);

Answer 1

getContentPane()是JFrame的方法。

Answer 2

这是因为你的基类是Frame,它没有getContentPane()函数也可以从JFrame继承,就可以调用getContentPane().add()函数了.

Answer 3

还有，楼主应该将setVisible(true);写在构造函数的最后一句，否则运行出现的画面是一片空白（Color.white）.

Answer 4

参见JavaDoc对JFrame的说明：
　　对于swing组件，不应该直接调用JFrame.add(),应该调用JFrame.getContentPane().add()
    而对于awt组件,则只能调用Frame.add();JApplet与Applet的情况与此类同,原因请参阅swing(卷2)

Answer 5

把setVisible(true);写在构造函数的最后一句试试

Answer 6

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;class MyFrame extends Frame 
{  Toolkit tool;
   Dimension dim;
   Color color;
   JTabbedPane jTabbedPane1;
   JPanel PanelA,PanelB;
   MyFrame(String s)
   {
      super(s);
        setVisible(true);
        tool=getToolkit();
        dim=tool.getScreenSize();
        setBounds(0,0,dim.width,dim.height);
        validate(); 
        JTabbedPane jTabbedPane1=new JTabbedPane();
        PanelA=new JPanel();
        PanelB=new JPanel();
        jTabbedPane1.addTab("login",PanelA);
        jTabbedPane1.addTab("Work List",PanelB);
        add(jTabbedPane1);
        setBackground(Color.red);
        addWindowListener( new WindowAdapter()
                                  {
                                     public void 
                                     windowClosing( WindowEvent e)
                                     {
                                            dispose();
                                            System.exit(0);
                                      }        
                                   }
                               );   
    }
   
}
class Menutree 
{  public static void main(String args[])
   { new MyFrame("目录系统");
   } 
}

Answer 7

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;class MyFrame extends JFrame 
{  Toolkit tool; Dimension dim;
   Color color;
   JTabbedPane jTabbedPane1;
   JPanel PanelA,PanelB;
   MyFrame(String s)
   {
        super(s);
        setVisible(true);
        tool=getToolkit();
        dim=tool.getScreenSize();
        setBounds(0,0,dim.width,dim.height);
        setBackground(Color.white);
        validate(); 
        JTabbedPane jTabbedPane1=new JTabbedPane();
        PanelA=new JPanel();
        PanelB=new JPanel();
        jTabbedPane1.addTab("login",PanelA);
        jTabbedPane1.addTab("Work List",PanelB);
        getContentPane().add(jTabbedPane1);
        addWindowListener( new WindowAdapter()
                                  {
                                     public void 
                                     windowClosing( WindowEvent e)
                                     {
                                            dispose();
                                            System.exit(0);
                                      }        
                                   }
                               );   
    }
   
}
class Menutree 
{  public static void main(String args[])
   { new MyFrame("目录系统");
   } 
}

Answer 8

注意应该把所有组件都填加完成后才能调用setVisible(true)  !!!可以这样写class Menutree 
{  public static void main(String args[])
   { MyFrame mf = new MyFrame("目录系统");
     mf.setVisible(true);
   } 
}注意要去掉MyFrame构造函数中的setVisible函数