My gui programme that contains (JPanel ,JFrame ,JLabel) JLabel : I Coded it To move from (0x, 0y) To (200x ,0y) Pixel by Pixel . it will start when i put the mouse on the panel called "p" ,but when i try to run this programme it's start correctly ,but when i put my mouse on the panel all thing stop to a few seconds The Label Moved to Point (200x, 0y) Any One Had Any Answer To Solve This Problem.

The Class Had The Problem :-

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


public class JFrameClass extends JFrame{
    JPanel p = new JPanel();
    JLabel l = new JLabel();
    
    public JFrameClass() {
        // TODO Auto-generated constructor stub
        setSize(800, 800);
        setLayout(null);
        setLocationRelativeTo(null);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        
        l.setBounds(0, 0, 50, 50);
        l.setBackground(new Color(16, 16, 16));
        l.setOpaque(true);
        
        p.setBounds(320, 320, 100, 100);
        p.setBackground(new Color(16, 16, 16));
        p.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseEntered(MouseEvent evt) {
                boolean wd = true;
                int x = 0;
                while(true) {
                    if(x == 200) wd = false;
                    if(!wd) break;
                    l.setLocation(x, 0);
                    x  ;
                    try {
                        Thread.sleep(10);
                    }catch(Exception e) {
                        
                    }
                }   
            }
        });
        
        
        add(p);
        add(l);
        
        
        
        setVisible(true);
    }
}

The Main Class That Run The JFrameClass class :-

public class Main {
    public static void main(String[] args) {
        new JFrameClass();
        
    }
}

CodePudding user response：

You're running your code on the Event-Dispatch-Thread. That's a no-no. Put the code in your mouseEntered into a SwingWorker.

SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
                 protected Void doInBackground() throws Exception {
                     for (int x = 0; x < 200; x  ) {
                         l.setVisible(false);
                         l.setLocation(x, 0);
                         l.setVisible(true);
                         try {
                             Thread.sleep(10);
                         }catch(Exception e) {
                             
                         }
                     }
                     return null;
                 }
             };
             worker.execute();

CodePudding user response：

Listener methods like mouseEntered() are expected to return quickly, within at most a few milliseconds, as Java will start processing the next user interface event only when the previous event processing has finished.

Your mouseEntered() will loop 200 times, with every iteration sleeping for 10msec. So, Java will pause its complete UI event handling until these 2 seconds have passed, meaning to completely freeze the UI for this time.

If you want to create a moving label, you need to use a Timer or something similar.