Delete Text from JLabel after 5 seconds?

问题

I wanted to know if there's any easy way to delete the content (text) from a JLabel after 5 seconds. Is that possible? Because I have a JLabel in a JFrame and it shows some internal errors from the program I'm coding and I want the JLabel to show the message for a couple of seconds and then go to blank. Any ideas?

回答1:

Simplest solution is to use a Swing Timer. It will prevent freezing the GUI and ensure proper Thread access (ie, UI modification is performed on the EDT).

Small demo example:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestLabelDelete {
    private JFrame frame;
    private JLabel label;

    protected void initUI() {
        frame = new JFrame(TestLabelDelete.class.getSimpleName());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        label = new JLabel("Some text to delete in 5 seconds");
        frame.add(label);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        Timer t = new Timer(5000, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                label.setText(null);
            }
        });
        t.setRepeats(false);
        t.start();
    }

    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                TestLabelDelete testLogin = new TestLabelDelete();
                testLogin.initUI();
            }

        });
    }

}

回答2:

Use Timer. Please see my example.

import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.Timer;

public class SourceCodeProgram {

    private static void createAndShowGUI() {
        // Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        // Create and set up the window.
        JFrame frame = new JFrame("HelloWorldSwing");
        frame.setMinimumSize(new Dimension(200, 300));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Add the ubiquitous "Hello World" label.
        final JLabel label = new JLabel("Hello World");
        frame.getContentPane().add(label);

        // Display the window.
        frame.pack();
        frame.setVisible(true);

        Timer timer = new Timer(5000, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                // Clear text or whatever you want
                label.setText("New text");
            }
        });
        // start Tick-Tack
        timer.start();
    }

    public static void main(String[] args) {
        // Schedule a job for the event-dispatching thread:
        // creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

Or you can write a separate class, which can clean label.

class JLabelCleaner {

    private JLabel label;
    private int waitSeconds;

    public JLabelCleaner(int waitSeconds, JLabel label) {
        this.label = label;
        this.waitSeconds = waitSeconds;
    }

    public void startCountdownFromNow() {
        Timer timer = new Timer(waitSeconds * 1000, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                label.setText("");
            }
        });
        timer.start();
    }
}

Now, you can use it whenever you need it in this way:

new JLabelCleaner(5, label).startCountdownFromNow();

Also see:

• How to Use Swing Timers

回答3:

There is an easy solution to this.

JLabel label = new JLabel("error text");
Thread.sleep(5000);
label.setText("");

Hope this helps!

EDIT: If you don't want the program to freeze for 5 secs you'll have to put this inside a Runnable.

回答4:

It's very easy to do... just create a new thread and write code to clear text on label, and make that thread to sleep for 5sec and then start it.

import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class LabelThread {
    private JLabel textLabel;

    public LabelThread() {
        try {
            JFrame frame  = new JFrame("Label");
            frame.setSize(500, 500);

            textLabel = new JLabel("Hiiii.... Kill me");
            frame.setContentPane(textLabel);

            frame.setVisible(true);

            MyThread thread = new MyThread();
            MyThread.sleep(5000);
            thread.start();
        } catch (InterruptedException ex) {

        }
    }
    class MyThread extends Thread{

        @Override
        public void run() {
            System.out.print("Running thread");
            textLabel.setText("");
        }

}
public static void main(String args[]){
    LabelThread labelThread = new LabelThread();
}
}

来源：https://stackoverflow.com/questions/14668151/delete-text-from-jlabel-after-5-seconds