关于内部窗体的问题

Question

我创建了多个内部窗体，但是发现当我关闭名为a的内部窗体，然后在想打开名为a的内部窗体就打不开了，就是说一个内部窗体只能显示一次。当关闭后就在无法显示，只能重新启动程序。
这为什么？应该怎么做？
谢谢各位大侠！！！

Answer 1

package jinxiaocun;/**
 * 注册
 */
import javax.swing.JInternalFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JComboBox;
import javax.swing.JPanel;
import javax.swing.event.InternalFrameEvent;
import javax.swing.event.InternalFrameListener;
import javax.swing.JOptionPane;import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.GridLayout;
public class LoginInternalFrameClass extends JInternalFrame{//注册窗体
    public LoginInternalFrameClass() {
        super("注册",false,true,false,true);
        setSize(350,500);
        setLayout(new GridLayout(5,1));
        panelName=new JPanel();
        textName=new JTextField(15);
        panelName.add(new JLabel("账号"));
        panelName.add(textName);        panelPassword=new JPanel();
        textPassword=new JPasswordField(15);
        panelPassword.add(new JLabel("密码"));
        panelPassword.add(textPassword);        panelPasswordOK=new JPanel();
        textPasswordOK=new JPasswordField(15);
        panelPasswordOK.add(new JLabel("确认密码"));
        panelPasswordOK.add(textPasswordOK);        panelType=new JPanel();
        textType=new JComboBox();
        textType.setEditable(true);
        textType.addItem("");
        textType.addItem("普通用户");
        textType.addItem("VIP");
        textType.addItem("管理员");
        panelType.add(new JLabel("身份"));
        panelType.add(textType);        panelButton=new JPanel();
        buttonOK=new JButton("确定");
        buttonNewly=new JButton("重置");
        buttonExit=new JButton("退出");        buttonOK.addActionListener(actionListener);
        buttonNewly.addActionListener(actionListener);
        buttonExit.addActionListener(actionListener);        panelButton.add(buttonOK);
        panelButton.add(buttonNewly);
        panelButton.add(buttonExit);        addInternalFrameListener(internalListener);        add(panelName);
        add(panelPassword);
        add(panelPasswordOK);
        add(panelType);
        add(panelButton);
    }
    private class InternalFrameClassListener implements InternalFrameListener{
        public void internalFrameOpened(InternalFrameEvent e) {
        }        public void internalFrameClosing(InternalFrameEvent e) {
            int i=JOptionPane.showConfirmDialog(null,"是否退出");
            if(i==0){
                setVisible(true);
            }
        }        public void internalFrameClosed(InternalFrameEvent e) {
        }        public void internalFrameIconified(InternalFrameEvent e) {
        }        public void internalFrameDeiconified(InternalFrameEvent e) {
        }        public void internalFrameActivated(InternalFrameEvent e) {
        }        public void internalFrameDeactivated(InternalFrameEvent e) {
        }    }
    private class LoginActionListener implements ActionListener{
        public void actionPerformed(ActionEvent event){
            String name=String.valueOf(textName.getText());
            String password=String.valueOf(textPassword.getPassword());
            String passwordOK=String.valueOf(textPasswordOK.getPassword());
            String type=String.valueOf(textType.getSelectedItem());
           if(event.getSource()==buttonOK){
               if(isLogin(name,password,passwordOK,type)){
                   if(sql.isLoginSqlServer(name,password,passwordOK,type)){
                       JOptionPane.showMessageDialog(null,"注册成功");
                       textName.setText("");
                       textPassword.setText("");
                       textPasswordOK.setText("");
                       textType.setSelectedItem("");
                   }
                   else{
                       JOptionPane.showMessageDialog(null,"系统繁忙，请与管理员联系！");
                   }
               }
           }
           else if(event.getSource()==buttonNewly){
               textName.setText("");
               textPassword.setText("");
               textPasswordOK.setText("");
               textType.setSelectedItem("");
           }
           else if(event.getSource()==buttonExit){
               int i=JOptionPane.showConfirmDialog(null,"是否退出");
               if(i==0){
                   setVisible(false);
               }
           }
        }
    }
    public boolean isLogin(String name,String password,String passwordOK,String type){
        if(name.equals("")){
            JOptionPane.showMessageDialog(null,"用户名不能为空");
            return false;
        }
        else if(name.length()<6){
            JOptionPane.showMessageDialog(null,"用户名长度不对");
            return false;
        }
        else if(name.length()>20){
            JOptionPane.showMessageDialog(null,"用户名长度超过范围");
            return false;
        }
        else if(password.equals("")){
            JOptionPane.showMessageDialog(null,"密码不能为空");
            return false;
        }
        else if(password.length()<6){
            JOptionPane.showMessageDialog(null,"密码长度不对");
            return false;
        }
        else if(password.length()>20){
            JOptionPane.showMessageDialog(null,"密码超过范围");
            return false;
        }
        else if(!passwordOK.equals(password)){
            JOptionPane.showMessageDialog(null,"密码和密码确认不一样");
            return false;
        }
        else if(type.equals("")){
            JOptionPane.showMessageDialog(null,"身份不能为空");
            return false;
        }
        return true;
    }
    private MySql sql=new MySql();
    private LoginActionListener actionListener=new LoginActionListener();
    private InternalFrameClassListener internalListener=new InternalFrameClassListener();
    private JPanel panelName,panelPassword,panelPasswordOK,panelType,panelButton;
    private JTextField textName;
    private JPasswordField textPassword,textPasswordOK;
    private JComboBox textType;
    private JButton buttonOK,buttonNewly,buttonExit;
}

Answer 2

public class TestFrame extends javax.swing.JFrame {
    
    /** Creates new form TestFrame */
    public TestFrame() {
        initComponents();
    }    // <editor-fold defaultstate="collapsed" desc=" 生成的代码 ">
    private void initComponents() {
        jFrame1 = new javax.swing.JFrame();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();        org.jdesktop.layout.GroupLayout jFrame1Layout = new org.jdesktop.layout.GroupLayout(jFrame1.getContentPane());
        jFrame1.getContentPane().setLayout(jFrame1Layout);
        jFrame1Layout.setHorizontalGroup(
            jFrame1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 400, Short.MAX_VALUE)
        );
        jFrame1Layout.setVerticalGroup(
            jFrame1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 300, Short.MAX_VALUE)
        );        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });        jButton2.setText("jButton2");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(44, 44, 44)
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING)
                    .add(jButton2)
                    .add(jButton1))
                .addContainerGap(283, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(87, 87, 87)
                .add(jButton1)
                .add(25, 25, 25)
                .add(jButton2)
                .addContainerGap(142, Short.MAX_VALUE))
        );
        pack();
    }// </editor-fold>    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO 将在此处添加您的处理代码：
        this.jFrame1.setVisible(false);
    }    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO 将在此处添加您的处理代码：
        this.jFrame1.setVisible(true);
    }
        public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new TestFrame().setVisible(true);
            }
        });
    }
    
    // 变量声明 - 不进行修改
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JFrame jFrame1;
    // 变量声明结束
    
}