//menu
package datapro;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
public class Menu {
    public static void main(String[] arg) throws Exception{
        final JFrame  jf=new JFrame("测试窗口");
        jf.setSize(300, 300);
        jf.setLocationRelativeTo(null);
        jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        jf.setVisible(true);

        JMenuBar menuBar = new JMenuBar();
        JMenu fileMenu = new JMenu("menu");
        menuBar.add(fileMenu);


        JMenuItem fiMenuItem = new JMenuItem("align");
        JMenuItem seMenuItem = new JMenuItem("calculator");
        JMenuItem exitMenuItem = new JMenuItem("exit");
        fileMenu.add(fiMenuItem);
        fileMenu.add(seMenuItem);
        fileMenu.addSeparator();       // 添加一条分割线
        fileMenu.add(exitMenuItem);

        LabelFrame panel1 = new LabelFrame();
        PanelFrame panel2 = new PanelFrame();
        jf.add(panel2);
        panel2.setVisible(false);
        //panel2.setVisible(false);
        jf.add(panel1);
        panel1.setVisible(false);

        fiMenuItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                jf.remove(panel1);
                jf.add(panel2);
                panel2.setVisible(true);    

                          }
        });

        seMenuItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                jf.remove(panel2);
                jf.add(panel1);
                panel1.setVisible(true);

            }
        });


        jf.setJMenuBar(menuBar);
        jf.setVisible(true);
    }
}

first
//
package datapro;  
import java.awt.*;  
    import javax.swing.*;  
    public class LabelFrame extends JPanel {  
        private final JButton []buttons;  
        private static final String []names = {"7","8","9","/","4","5","6","*","1","2","3","-","0",".","=","+"};  
        JTextField displayField=new JTextField(20);   
        JPanel p = new JPanel (new GridLayout (4,4,3,3));  
        public LabelFrame()  
        {  
           // super("Calculator"); 
            setLayout (new BorderLayout());  
            buttons = new JButton[names.length];  
            for (int i=0;i<names.length;i++) {  
                buttons[i] = new JButton (names[i]);  
                p.add (buttons[i]);  
            }  
            this.add (displayField,BorderLayout.NORTH);  
            this.add (p,BorderLayout.CENTER);  

        }  

    }  
//
package datapro;
import java.awt.*;
import javax.swing.JPanel;
import javax.swing.*;
import java.awt.event.*;
public class PanelFrame extends JPanel {
    private final JLabel label1;
    private final JLabel label2;
    private JTextField Field1;
    private JTextField Field2;
    private JButton Button1 = new JButton(" Ok ");
    private JButton Button2 = new JButton("Cancle");
    private JButton Button3 = new JButton(" Help ");
    public final JCheckBox checkbox1;
    public final JCheckBox checkbox2;
    protected BorderLayout layout;
    //protected Container container;

    public PanelFrame()
    {
        //super("Align");
        JPanel panel = new JPanel();
        panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));    
        JPanel panel2 = new JPanel();
        panel2.setLayout(new BoxLayout(panel2, BoxLayout.Y_AXIS));
        JPanel panel3 = new JPanel();
        panel3.setLayout(new BoxLayout(panel3, BoxLayout.Y_AXIS));
        JPanel panel6 = new JPanel();
        panel6.setLayout(new BoxLayout(panel6, BoxLayout.Y_AXIS));
        JPanel panel4 = new JPanel();
        panel4.setLayout(new FlowLayout());
        JPanel panel5 = new JPanel();
        //panel5.setLayout(new BoxLayout(panel5, BoxLayout.X_AXIS));
        panel5.setLayout(new FlowLayout());
        layout=new BorderLayout();
        //container=getContentPane();
        setLayout(layout);
        Box box1 = Box.createVerticalBox();
        //Dimension preferredSize = new Dimension(70,40);
        panel.add(box1);
        box1.add(Box.createRigidArea(new Dimension(15,30)));
        box1.add(Button1);
        box1.add(box1.createVerticalStrut(20));
        box1.add(Button2);
        //box1.createVerticalStrut(100);
        box1.add(box1.createVerticalStrut(20));
        box1.add(Button3);
        this.add(panel,BorderLayout.EAST);
        Box box2 = Box.createVerticalBox();
        box2.add(Box.createRigidArea(new Dimension(20,50)));
        panel2.add(box2);
        checkbox1 = new JCheckBox("snap to Grid");
        box2.add(checkbox1);
        box2.add(box2.createVerticalStrut(10));
        checkbox2 = new JCheckBox("show Grid");
        box2.add(checkbox2);
        this.add(panel2, BorderLayout.WEST);
        Box box3 = Box.createVerticalBox();

        box3.add(Box.createRigidArea(new Dimension(70,30)));
        panel3.add(box3);
        Box box4 = Box.createVerticalBox();
        //box4.add(box4.createHorizontalStrut(20));
        //panel6.add(box4);
        //this.add(panel6, BorderLayout.EAST);
// Box box5 = Box.createVerticalBox();
        label1 = new JLabel("X:");
        Field1 = new JTextField(5);
        panel4.add(label1);
        panel4.add(Field1);
        box3.add(panel4);
// box4.add(label1);
// Field1.setPreferredSize(new Dimension(10,40));
// box5.add(Field1);
// panel4.add(box4);
// panel5.add(box5);
// box3.add(panel4);
        label2 = new JLabel("Y:");
        Field2 = new JTextField(5);
        panel5.add(label2);
        panel5.add(Field2);
        box3.add(panel5);
        //box3.add(panel5);
        //label2 = new JLabel("Y:");
        //Field2 = new JTextField(5);
        //Box box5 = Box.createVerticalBox();
        //box5.add(label2);
        //box5.add(Field2);
        //panel5.add(box5);

        this.add(panel3, BorderLayout.CENTER);
    }

}