How to delay an answer while not freezing the thread?

Question

Simple question. Thread.sleep(x) freezes the entire code so even Buttons stay the way they are (pressed unpressed whatever)

I want to basicially click a button, "wait" for the computer to do it's thing for x amount of time and then output something.

public class bsp extends JFrame {
DrawPanel drawPanel = new DrawPanel();

public bsp() {
    setSize(600,600);
    JButton Hit = new JButton("Hit him");
    Hit.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            try {
                Thread.sleep(1500);
            } catch (InterruptedException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            System.out.println("I hit you back!");
            
        }
    });
    Hit.setSize(80, 30);
    Hit.setLocation(200, 400);
    add(Hit);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    add(drawPanel);
    setVisible(true);

}

private static class DrawPanel extends JPanel {

    protected void paintComponent(Graphics g) {
        
    }
}

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

}

}

As you can see, the button "stays" pressed and the whole program is frozen. But I basicially want to simulate the "A.I." thinking before answering, without freezing everything.

Instead of sleeping the thread, set a [`Timer`](https://docs.oracle.com/javase/tutorial/uiswing/misc/timer.html). — khelwood, Jul 26 '20 at 10:58

Darkmoon Chief · Accepted Answer · 2020-07-26T11:39:17.463

0

Consider using a Timer to prevent main thread from freezing :

import javax.swing.*;
import java.awt.event.*;

        ActionListener task = new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
             
            }
        };
        Timer countdown = new Timer(1000 ,task);
        countdown.setRepeats(false);
        countdown.start();

where 1000 is the delay time in milliseconds and inside the actionPerformed function is where your code executes after the delay time set.

edited Jul 26 '20 at 11:39

answered Jul 26 '20 at 11:02

Darkmoon Chief

138
6

1

Also https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/Executors.html is another option, see the ScheduledExecutorService. – Jason C Jul 26 '20 at 11:06
1

So if I use the delay... where would I implement other computations? Like say I want to add a simple "thinking..." while this delay is still happening? – Razak Jul 26 '20 at 11:22
Add the thinking... text before the code I wrote then inside the run() function hide the text using visibility property. – Darkmoon Chief Jul 26 '20 at 11:25
2

@Razak: this answer is incorrect in that Darkmoon is recommending the *wrong* Timer. You should not use a `java.util.Timer` as this runs afoul of Swing threading rules, but always for Swing programs use a `javax.swing.Timer`, aka a "Swing Timer". The former will cause your program to fail unexpectedly and intermittently with threading errors that can be hard to debug while the latter will work correctly. – DontKnowMuchBut Getting Better Jul 26 '20 at 11:29
Will rectify my answer. Thank you! – Darkmoon Chief Jul 26 '20 at 11:30
1

Don't know much is indeed very much correct – Hovercraft Full Of Eels Jul 26 '20 at 11:32
2

You have not fixed your answer. -1. Please understand how to use Swing Timers before answering about them – Hovercraft Full Of Eels Jul 26 '20 at 11:34
Edited again lmao. – Darkmoon Chief Jul 26 '20 at 11:39

How to delay an answer while not freezing the thread?

1 Answers1