Changing JTextField's text while iterating or inside a loop

Question

Let's say I have a JTextField "status" and I'm running this code:

status = new JTextField(50);
add(status);

for (int i=0; i<10000; i++) {
     status.setText("bla bla - "+ i);
     System.out.println("bla bla - "+ i);
}

My problem is that right now while the loop is running nothing happened in the JTextField's text and only when the loop end the label is "bla bla - 10000".

I want to make something like a status bar but cant update this status bar "online". I also tried to do the update in a thread but ended with the same result.

Can someone show my how I can present a text in a GUI while iterating or looping?

Don't block the EDT (Event Dispatch Thread) - the GUI will 'freeze' when that happens. Instead implement a `SwingWorker` for long running tasks. See [Concurrency in Swing](http://docs.oracle.com/javase/tutorial/uiswing/concurrency/) for more details. — Andrew Thompson, Apr 15 '13 at 08:43
[This](http://stackoverflow.com/questions/6774414/why-is-my-jtextarea-not-updating) should help. — Kazekage Gaara, Apr 15 '13 at 08:44
I would do it this way: http://nenadbulatovic.blogspot.com/2014/05/java-changing-jtextfields-text-while.html — Nenad Bulatović, May 15 '14 at 19:15

score 7 · Accepted Answer · edited May 23 '17 at 10:29

Use a SwingWorker to split UI-update and long running tasks.

Take a few minutes to read the end of the Swing tag wiki and follow the provided links.

Here is a small example of such code:

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

public class TestSwingWorker {

    private JTextField progressTextField;

    protected void initUI() {
        final JFrame frame = new JFrame();
        frame.setTitle(TestSwingWorker.class.getSimpleName());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JButton button = new JButton("Clik me to start work");
        button.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                doWork();
            }
        });
        progressTextField = new JTextField(25);
        progressTextField.setEditable(false);
        frame.add(progressTextField, BorderLayout.NORTH);
        frame.add(button, BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);
    }

    protected void doWork() {
        SwingWorker<Void, Integer> worker = new SwingWorker<Void, Integer>() {
            @Override
            protected Void doInBackground() throws Exception {
                for (int i = 0; i < 100; i++) {
                    // Simulates work
                    Thread.sleep(10);
                    publish(i);
                }
                return null;
            }

            @Override
            protected void process(List<Integer> chunks) {
                progressTextField.setText(chunks.get(chunks.size() - 1).toString());
            }

            @Override
            protected void done() {
                progressTextField.setText("Done");
            }
        };
        worker.execute();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TestSwingWorker().initUI();
            }
        });
    }
}

Costis Aivalis · Answer 2 · 2013-04-16T09:36:33.377

3

Use a javax.swing.Timer. Here is an example that shows you how:

private void refreshMyTextField() {       
    Timer timer1 = new Timer(100, new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            jTextField1.setText("bla bla - "+(j++));
        }
    });
    timer1.start();  
}

edited Apr 16 '13 at 09:36

answered Apr 15 '13 at 08:57

Costis Aivalis

13,680
3
46
47

score 0 · Answer 3 · answered Apr 15 '13 at 08:52

0

Use Timer class which executes a task in intervals. Because you don't use interval, what you get is the last value 10000. You can't see previous values because of interval absence.

Regards,

answered Apr 15 '13 at 08:52

Ravi Trivedi

2,340
2
14
20

score 0 · Answer 4 · answered Apr 15 '13 at 09:02

0

try to use status.setText(""); before status.setText("bla bla - "+ i);

answered Apr 15 '13 at 09:02

komal kadam

185
1
1
11

3

That won't help. As long as he is blocking the EDT, no changes can appear in the UI. – Guillaume Polet Apr 15 '13 at 09:02

Changing JTextField's text while iterating or inside a loop

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