DocumentListener with Thread.sleep

Question

I want to know when I am writing and when I am deleting, but, after a 0.5 second delay, it will tell me "You stopped writing/deleting" However, it only shows that message and it delete or write after a half second delay.

How could I use Thread.sleep(500); correctly?

My current source code:

import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;


public class TextChangedFrame extends JFrame {

    JTextField textField = new JTextField("Put your text here");
    JLabel label = new JLabel("You have written: ");

    public TextChangedFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300, 100);
        setLayout(new BorderLayout());
        getContentPane().add(textField, BorderLayout.CENTER);
        getContentPane().add(label, BorderLayout.SOUTH);
        textField.getDocument().addDocumentListener(new DocumentListener() {

            public void insertUpdate(DocumentEvent e) {
                label.setText("I'm writting: " + textField.getText());
                try {
                    Thread.sleep(500);
                } catch (InterruptedException ex) {

                }
                label.setText("I stopped writing");
            }

            public void removeUpdate(DocumentEvent e) {
                label.setText("I'm deleting");
                try {
                    Thread.sleep(500);
                } catch (InterruptedException ex) {

                }
                label.setText("I stopped deleting");
            }

            public void changedUpdate(DocumentEvent e) {
            }
        });
    }

    public static void main(String[] args) {
        TextChangedFrame frame = new TextChangedFrame();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

Answer 1

Again, use a Swing Timer to do the dirty work. What you do is whenever you edit or delete, call re-start on the Timer to re-set the timer and start it. The restart() method will stop the Timer if it is running.

     public void insertUpdate(DocumentEvent e) {
        label.setText(EDITING);
        writeDeleteTimer.restart();
     }

For example:

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.*;

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

@SuppressWarnings("serial")
public class TextChangedFrame extends JPanel {

   public static final String STOPPED_EDITING = "No Longer Editing or Deleting";
   private static final String EDITING = "Editing";
   private static final String DELETING = "Deleting";
   private static final int TIMER_DELAY = 500;
   private static final int PREF_W = 400;
   private static final int PREF_H = 100;
   private JTextField textField = new JTextField("Put your text here");
   private JLabel label = new JLabel("You have written: ");
   private ActionListener timerListener = new TimerListener();
   private Timer writeDeleteTimer = new Timer(TIMER_DELAY, timerListener);

   public TextChangedFrame() {
      setLayout(new BorderLayout());
      add(textField, BorderLayout.CENTER);
      add(label, BorderLayout.SOUTH);
      textField.getDocument().addDocumentListener(new DocumentListener() {

         public void insertUpdate(DocumentEvent e) {
            label.setText(EDITING);
            writeDeleteTimer.restart();
         }

         public void removeUpdate(DocumentEvent e) {
            label.setText(DELETING);
            writeDeleteTimer.restart();
         }

         public void changedUpdate(DocumentEvent e) {
         }
      });
   }

   @Override
   public Dimension getPreferredSize() {
      return new Dimension(PREF_W, PREF_H);
   }

   private class TimerListener implements ActionListener {
      @Override
      public void actionPerformed(ActionEvent evt) {
         label.setText(STOPPED_EDITING);
         Timer timer = (Timer) evt.getSource();
         timer.stop();
      }
   }

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

      JFrame frame = new JFrame("TextChangedFrame");
      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();
         }
      });
   }
}

---

Answer edited: no need to recreate the Timer object. Simply call restart() on it as it will stop the current Timer if it's running.

Answer 2

This question is fairly poor, and is not very clear, so I cannot give an exact answer until the question is cleared up.

It seems currently that you are using Thread.sleep(500) to cause a delay for 500 milliseconds. In most programs, this will work.

Thread.sleep(int x) suspends (or freezes, depending on who you ask) the current operation for x milliseconds (in your case, 500 milliseconds).

In the application you are using, you are using it to suspend a change in text. Due to it's location, it currently freezes the entire swing box, and it is not recovering.

If you HAVE to use Thread.sleep(int x), then I would recommend that you save the text you are using as a String, then update the TextChangedFrame after you update the String. This allows you to suspend operations, without suspending the TextChangedFrame.

PsuedoCode:

String oldString = "old string";
String newString = "new string";

// setup your dialog/popup here, with oldString

Thread.sleep(500);

// modify the dialog/popup here, changing oldString to newString

and that should avoid any freezing issues. (which I think, with the question and comments, your problem is).

A better solution would be to use Swing Timers, as mentioned by Hovercraft Full Of Eels in his comment