如何使用延迟的while循环每次更新jLabel

Question

   private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
  int count = jSlider1.getValue(); 
  int delay = jSlider2.getValue();
    int valueOfSlider = jSlider2.getValue();
     int valueOfSlider2 = jSlider1.getValue();

while (count > 0) 
{ 
    count--;
    String count2 = ""+count; 
  jLabel3.setText(count2);
try {Thread.sleep(delay); }
catch (InterruptedException ie) { }

 }

它最终将显示jLabel上的最终数字,但它不会逐步更新数字.任何帮助

Answer 1

Swing是单线程的.因此,在EDT中永远不应该进行长时间运行的任务.这包括睡觉.相反,使用javax.swing.Timer.这将延迟后台线程,然后发布要在EDT中执行的操作.

也可以看看:

• 如何使用摆动计时器

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
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;

public final class JLabelUpdateDemo {

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

    private static void createAndShowGUI(){
        final JFrame frame = new JFrame("Update JLabel Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(new FlowLayout());
        frame.getContentPane().add(JTimerLabel.getInstance());
        frame.setSize(new Dimension(275, 75)); // used for demonstration purposes
        //frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

        Timer t = new Timer(1000, new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                int val = Integer.valueOf(JTimerLabel.getInstance().getText());
                JTimerLabel.getInstance().setText(String.valueOf(++val));
            }
        });
        t.start();
    }

    private static final class JTimerLabel extends JLabel{
        private static JTimerLabel INSTANCE;

        private JTimerLabel(){
            super(String.valueOf(0));
            setFont(new Font("Courier New", Font.BOLD,  18));
        }

        public static final JTimerLabel getInstance(){
            if(INSTANCE == null){
                INSTANCE = new JTimerLabel();
            }

            return INSTANCE;
        }
    }
}

此SSCCE模仿计数器,该计数器将从0每秒开始计数(即更新JLabel实例),直到应用程序终止.