在打开另一个JFrame之前关闭一个JFrame

Question

I want to close completely one JFrame before opening another .

Consider the code :

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.InetAddress;
import javax.swing.*;
import javax.swing.border.EmptyBorder;


/**
 * 
 * @author X
 *
 */
class ServerConnect extends JFrame implements ActionListener
{
    private static final long serialVersionUID = 1L;
    private JTextField m_serverIP;
    private JTextField m_serverPort; // you can use also JPasswordField
    private JButton m_submitButton;

    // location of the jframe
    private final int m_centerX = 500;
    private final int m_centerY = 300;

    // dimensions of the jframe
    private final int m_sizeX = 1650;
    private final int m_sizeY = 150;


    /**
     * Ctor
     */
    ServerConnect()
    {
        this.setTitle("Sever Side Listener");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        m_serverIP = new JTextField(20);
        m_serverPort = new JTextField(20);

        JPanel gui = new JPanel(new BorderLayout(3,3));
        gui.setBorder(new EmptyBorder(5,5,5,5));
        gui.setSize(m_sizeX , m_sizeY);
        this.setContentPane(gui);

        JPanel labels = new JPanel(new GridLayout(0,1));
        JPanel controls = new JPanel(new GridLayout(0,1));
        gui.add(labels, BorderLayout.WEST);
        gui.add(controls, BorderLayout.CENTER);

        labels.add(new JLabel("Server IP: "));
        controls.add(m_serverIP);
        labels.add(new JLabel("Server Port: "));
        controls.add(m_serverPort);
        m_submitButton = new JButton("Start Listening");
        m_submitButton.addActionListener(this);

        gui.add(m_submitButton, BorderLayout.SOUTH);
        this.setLocation(m_centerX , m_centerY);
        this.setSize(m_sizeX , m_sizeY);
        this.pack();
        this.setVisible(true);
    }

    public static void main(String[] args) {
        new ServerConnect();
    }

    @Override
    public void actionPerformed(ActionEvent event) {

        Object object = event.getSource();
        if (object == this.m_submitButton)
        {
            // grab all values from the connection box 
            // if one of them is missing then display an alert message 

            String ip = this.m_serverIP.getText().trim();
            String port = this.m_serverPort.getText().trim();

            if (ip.length() == 0)
            {
                JOptionPane.showMessageDialog(null, "Please enter IP address !");
                return;
            }

            if (port.length() == 0)
            {
                JOptionPane.showMessageDialog(null, "Please enter Port number!");
                return;
            }

            int s_port = 0;

            try
            {
                // try parse the Port number 
                // throws exception when an incorrect IP address 
                // is entered , and caught in the catch block 
                s_port = Integer.parseInt(port);
            }

            catch(Exception exp)
            {
                JOptionPane.showMessageDialog(null, "Port number is incorrect!");
                return;
            }

            try
            {
                // try parse the IP address 
                // throws exception when an incorrect IP address 
                // is entered , and caught in the catch block 
                InetAddress.getByName(ip);
            }

            catch(Exception exp)
            {
                JOptionPane.showMessageDialog(null, "IP address is incorrect!");
                return;
            }
            this.setVisible(false);
            new ServerGUI(ip , s_port);
        }
    }
}

In actionPerformed() after the user had entered the IP number and port , I set the window to false , ie :

        this.setVisible(false);      // don't show the current window
        new ServerGUI(ip , s_port);  // open another JFrame

I want to close the current JFrame completely, not to set its visibility to false.

How can I do that ?

Regards

Answer 1

Your problem appears that if you call close on the JFrame, the program will exit since you've set its setDefaultCloseOperation to setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); .

Options:

• Use a different defaultCloseOperation, one that doesn't close the application, perhaps JFrame.DISPOSE_ON_CLOSE .
• Use a JDialog initially instead of a JFrame. These types of windows can't shut down the application. Here is the JDialog and JOptionPane Tutorial
• Don't swap JFrames at all, but rather swap views by using a CardLayout. The CardLayout Tutorial link

My own preference is to use a CardLayout as much as possible to avoid annoying the user who usually doesn't appreciate having a bunch of windows flung at him. I also use modal JDialogs when I want to get information from the user in a modal fashion, ie, where the application absolutely cannot move forward until the user gives the requested information, and non-modal dialogs to present program state monitoring information for the user. I almost never use multiple JFrames in a single application.

---

Edit
As an aside, I almost never create classes that extend JFrame or any top-level window since I find that much too restricting. Instead most of my GUI type classes are geared towards creating JPanels. The advantage to this is then I can decide when and where I want to put the JPanel, and can change my mind at any time. It could go into a JFrame, a JDialog, a JOptionPane, be a card that is swapped in a CardLayout,... anywhere.

---

Edit 2

For example, here's a small program that uses your code, slightly modified, and puts it into a JDialog:

My code:

import java.awt.Dialog.ModalityType;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

import javax.swing.*;

public class MyServerMain extends JPanel {
   private JTextField serverIp = new JTextField(8);
   private JTextField serverPort = new JTextField(8);
   private ServerConnect serverConnect = new ServerConnect();
   private JDialog serverConnectDialog = null;

   public MyServerMain() {
      serverIp.setFocusable(false);
      serverPort.setFocusable(false);

      add(new JLabel("Server IP:"));
      add(serverIp);
      add(new JLabel("Server Port:"));
      add(serverPort);
      add(new JButton(new SetUpServerAction("Set Up Server", KeyEvent.VK_S)));
   }

   private class SetUpServerAction extends AbstractAction {
      public SetUpServerAction(String name, int keyCode) {
         super(name);
         putValue(MNEMONIC_KEY, keyCode);
      }

      @Override
      public void actionPerformed(ActionEvent evt) {
         if (serverConnectDialog == null) {
            Window owner = SwingUtilities.getWindowAncestor(MyServerMain.this);
            serverConnectDialog = new JDialog(owner, "Server Set Up",
                  ModalityType.APPLICATION_MODAL);

            serverConnectDialog.getContentPane().add(serverConnect);
            serverConnectDialog.pack();
            serverConnectDialog.setLocationRelativeTo(owner);
         }
         serverConnectDialog.setVisible(true);

         // when here, the dialog is no longer visible
         // so extract information from the serverConnect object
         serverIp.setText(serverConnect.getServerIp());
         serverPort.setText(serverConnect.getServerPort());
      }
   }

   private static void createAndShowGui() {
      MyServerMain mainPanel = new MyServerMain();

      JFrame frame = new JFrame("My Server Main");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

Your modified code:

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.InetAddress;

import javax.swing.*;
import javax.swing.border.EmptyBorder;

class ServerConnect extends JPanel implements ActionListener {
   private static final long serialVersionUID = 1L;
   private JTextField m_serverIP;
   private JTextField m_serverPort; // you can use also JPasswordField
   private JButton m_submitButton;

   // location of the jframe
   private final int m_centerX = 500;
   private final int m_centerY = 300;

   // dimensions of the jframe
   private final int m_sizeX = 1650;
   private final int m_sizeY = 150;

   ServerConnect() {
      m_serverIP = new JTextField(20);
      m_serverPort = new JTextField(20);

      JPanel gui = new JPanel(new BorderLayout(3, 3));
      gui.setBorder(new EmptyBorder(5, 5, 5, 5));
      gui.setSize(m_sizeX, m_sizeY);
      setLayout(new BorderLayout()); // !!
      add(gui, BorderLayout.CENTER);

      JPanel labels = new JPanel(new GridLayout(0, 1));
      JPanel controls = new JPanel(new GridLayout(0, 1));
      gui.add(labels, BorderLayout.WEST);
      gui.add(controls, BorderLayout.CENTER);

      labels.add(new JLabel("Server IP: "));
      controls.add(m_serverIP);
      labels.add(new JLabel("Server Port: "));
      controls.add(m_serverPort);
      m_submitButton = new JButton("Start Listening");
      m_submitButton.addActionListener(this);

      gui.add(m_submitButton, BorderLayout.SOUTH);
      this.setLocation(m_centerX, m_centerY);
      this.setSize(m_sizeX, m_sizeY);
      // !! this.pack();
      // !! this.setVisible(true);
   }

   public static void main(String[] args) {
      new ServerConnect();
   }

   @Override
   public void actionPerformed(ActionEvent event) {

      Object object = event.getSource();
      if (object == this.m_submitButton) {
         // grab all values from the connection box
         // if one of them is missing then display an alert message

         String ip = this.m_serverIP.getText().trim();
         String port = this.m_serverPort.getText().trim();

         if (ip.length() == 0) {
            JOptionPane.showMessageDialog(null, "Please enter IP address !");
            return;
         }

         if (port.length() == 0) {
            JOptionPane.showMessageDialog(null, "Please enter Port number!");
            return;
         }

         int s_port = 0;

         try {
            // try parse the Port number
            // throws exception when an incorrect IP address
            // is entered , and caught in the catch block
            s_port = Integer.parseInt(port);
         }

         catch (Exception exp) {
            JOptionPane.showMessageDialog(null, "Port number is incorrect!");
            return;
         }

         try {
            // try parse the IP address
            // throws exception when an incorrect IP address
            // is entered , and caught in the catch block
            InetAddress.getByName(ip);
         }

         catch (Exception exp) {
            JOptionPane.showMessageDialog(null, "IP address is incorrect!");
            return;
         }

         // !! this.setVisible(false);
         // !! new ServerGUI(ip , s_port);
         // !!
         Window ownerWindow = SwingUtilities.getWindowAncestor(this);
         ownerWindow.dispose();
      }
   }

   // !!
   public String getServerIp() {
      return m_serverIP.getText();
   }

   // !!
   public String getServerPort() {
      return m_serverPort.getText();
   }
}

Answer 2

Hope this another_Frame frm = new another_Frame(); frm.setVisible(true); this.dispose();// this represent the fram to close another_Frame frm = new another_Frame(); frm.setVisible(true); this.dispose();// this represent the fram to close