Forcing a GUI update inside of a thread - JSlider updates

问题

I'm trying to simulate betting results on a "horse race" by setting JSlider positions within a loop utilizing random numbers. My problem is that, of course, I can't get the GUI to update while the thread is executing, whereby my JSliders do not seem to be racing, they are going from start to finish. I've tried playing around with the code and separating them out into different methods, but I can't get around the single threaded swing issue. Is there a way to force an update or stop the thread to update the GUI and restart the process until the conditions are met?

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JOptionPane;



public class HorseMain extends JApplet {



/**
 * Initializes the applet MainInterface
 */
@Override
public void init() {
           try {
        for (javax.swing.UIManager.LookAndFeelInfo info :     javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(MainInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(MainInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(MainInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(MainInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the applet */
    try {
        java.awt.EventQueue.invokeAndWait(new Runnable() {
            public void run() {
                initComponents();
            }
        });
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}


 @SuppressWarnings("unchecked")

   private void initComponents() {


    jPanel1 = new javax.swing.JPanel();
    jSlider1 = new javax.swing.JSlider(1,400,1);
    jSlider2 = new javax.swing.JSlider(1,400,1);
    jSlider3 = new javax.swing.JSlider(1,400,1);
    jSlider4 = new javax.swing.JSlider(1,400,1);
    jSlider5 = new javax.swing.JSlider(1,400,1);
    jSlider6 = new javax.swing.JSlider(1,400,1);
    jPanel2 = new javax.swing.JPanel();
    jCheckBox1 = new javax.swing.JCheckBox();
    jCheckBox2 = new javax.swing.JCheckBox();
    jCheckBox3 = new javax.swing.JCheckBox();
    jComboBox1 = new javax.swing.JComboBox();
    jTextField1 = new javax.swing.JTextField();
    jLabel2 = new javax.swing.JLabel();
    jPanel3 = new javax.swing.JPanel();
    jPanel4 = new javax.swing.JPanel();
    jTextField2 = new javax.swing.JTextField();
    jButton1 = new javax.swing.JButton();
    jTextField3 = new javax.swing.JTextField();
    jLabel1 = new javax.swing.JLabel();



    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jSlider1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        .addComponent(jSlider2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        .addComponent(jSlider3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        .addComponent(jSlider4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        .addComponent(jSlider5, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        .addComponent(jSlider6, javax.swing.GroupLayout.Alignment.TRAILING,javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jSlider1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jSlider3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jSlider4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jSlider5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jSlider6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
    );

    jCheckBox1.setText("Win");

    jCheckBox2.setText("Place");

    jCheckBox3.setText("Show");

    jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Horse 1", "Horse 2",
    "Horse 3", "Horse 4", "Horse 5", "Horse 6"}));

    jTextField1.setText("1");

    jLabel2.setText("Bet Amount:");

    javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
    jPanel2.setLayout(jPanel2Layout);
    jPanel2Layout.setHorizontalGroup(
        jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel2Layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jComboBox1, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGroup(jPanel2Layout.createSequentialGroup()
                    .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jCheckBox3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jCheckBox2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jCheckBox1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                        .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                            .addComponent(jLabel2, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jTextField1, javax.swing.GroupLayout.Alignment.LEADING)))
                    .addGap(0, 0, Short.MAX_VALUE)))
            .addContainerGap())
    );
    jPanel2Layout.setVerticalGroup(
        jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel2Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(10, 10, 10)
            .addComponent(jCheckBox1)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jCheckBox2)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jCheckBox3)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jLabel2)
            .addGap(5, 5, 5)
            .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );

    javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
    jPanel3.setLayout(jPanel3Layout);
    jPanel3Layout.setHorizontalGroup(
        jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 127, Short.MAX_VALUE)
    );
    jPanel3Layout.setVerticalGroup(
        jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 65, Short.MAX_VALUE)
    );

    jTextField2.setText("Winnings");

    jButton1.setText("RACE!");
     jButton1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });

    jTextField3.setText("500");

    jLabel1.setText("Bank:");

    javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
    jPanel4.setLayout(jPanel4Layout);
    jPanel4Layout.setHorizontalGroup(
        jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel4Layout.createSequentialGroup()
            .addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(jPanel4Layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jTextField3))
                .addGroup(jPanel4Layout.createSequentialGroup()
                    .addGap(22, 22, 22)
                    .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 46, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 109, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(0, 47, Short.MAX_VALUE)))
            .addGap(160, 160, 160)
            .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 115, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(23, 23, 23))
    );
    jPanel4Layout.setVerticalGroup(
        jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel4Layout.createSequentialGroup()
            .addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                .addGroup(jPanel4Layout.createSequentialGroup()
                    .addGap(37, 37, 37)
                    .addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(jLabel1))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 14, Short.MAX_VALUE)
                    .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(jPanel4Layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
            .addContainerGap())
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );

}
 private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         


  if (evt.getSource() == jButton1)
  { 
      while (END!=1)
      {
          END=race();
          timer();
      }             

  }  




}
public void timer()
  {
      for(int i=0; i<6; i++)
      {            
       try {
            Thread.sleep(250L);
    } catch (InterruptedException e) {
             e.printStackTrace();
             } 


      }                  
          }
public int race()
{   int end=0;
    boolean racing=true;      

   stride1 = horse1.trot();
   pos1+= stride1;
   jSlider1.setValue(pos1);
   stride2 = horse2.trot();
   pos2+= stride2;
   jSlider2.setValue(pos2);
   stride3 = horse3.trot();
   pos3+= stride3;
   jSlider3.setValue(pos3);
   stride4 = horse1.trot();
   pos4+= stride4;
   jSlider4.setValue(pos4);
   stride5 = horse5.trot();
   pos5+=stride5;
   jSlider5.setValue(pos5);
   stride6 = horse6.trot();
   pos6+=stride5;
   jSlider6.setValue(pos6);
   System.out.println(stride1);
   System.out.println(stride2);
   System.out.println(stride3);
   System.out.println(stride4);
   System.out.println(stride5);
   System.out.println(stride6);
   System.out.println(pos1);
   System.out.println(pos2);
  if (pos1>=400 || pos2>=400 || pos3>=400 || pos4>=400 || pos5>=400 || pos6>=400)
  end = 1;    

    return end;
}
private javax.swing.JButton jButton1;
private javax.swing.JCheckBox jCheckBox1;
private javax.swing.JCheckBox jCheckBox2;
private javax.swing.JCheckBox jCheckBox3;
private javax.swing.JComboBox jComboBox1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;
private javax.swing.JPanel jPanel4;
private javax.swing.JSlider jSlider1;
private javax.swing.JSlider jSlider2;
private javax.swing.JSlider jSlider3;
private javax.swing.JSlider jSlider4;
private javax.swing.JSlider jSlider5;
private javax.swing.JSlider jSlider6;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
   int stride1=0;
   int stride2=0;
   int stride3=0;
   int stride4=0;
   int stride5=0;
   int stride6=0;
   int pos1=0;
   int pos2=0;
   int pos3=0;
   int pos4=0;
   int pos5=0;
   int pos6=0;               
   Horse horse1 = new Horse();
   Horse horse2 = new Horse();
   Horse horse3 = new Horse();
   Horse horse4 = new Horse();
   Horse horse5 = new Horse();
   Horse horse6 = new Horse();
   private int END=0;

回答1:

Here is your problem:

public void timer() {
    for(int i=0; i<6; i++) {
        try {
            Thread.sleep(250L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

This code is executing and blocking the Event Dispatching Thread (a.k.a. EDT) in this call: Thread.sleep(250L). The EDT is a single and special thread where Swing component creation and updates take place. If you have a heavy task running in the EDT then your GUI will freeze and Swing components won't be able to work (or even display).

Take a look to Concurrency in Swing trail to learn about concurrency in Swing.

You can use a Swing Timer to do periodic updates at a fixed rate of time. For instance something like this:

final JSlider horse1 = new JSlider(0, 100, 0);
final JSlider horse2 = new JSlider(0, 100, 0);
final JSlider horse3 = new JSlider(0, 100, 0);

Timer timer = new Timer(100, new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        Random random = new Random();

        int horse1Value = horse1.getValue();
        horse1Value += random.nextInt(101 - horse1Value);
        horse1.setValue(horse1Value);

        int horse2Value = horse2.getValue();
        horse2Value += random.nextInt(101 - horse2Value);
        horse2.setValue(horse2Value);

        int horse3Value = horse3.getValue();
        horse3Value += random.nextInt(101 - horse3Value);
        horse3.setValue(horse3Value);

        if(horse1Value == 100 && horse2Value == 100 && horse3Value == 100) {
            System.out.println("Race finished!");
            Timer timer = (Timer)e.getSource();
            timer.stop();
        }
    }
});
timer.setRepeats(true);
timer.start();

回答2:

Put all the horse race calculation into an own thread. You can do anything in there including Thread.sleep().

To move the sliders call SwingUtilities.invokeLater(). This way single threaded Swing and your horse run neetly side by side.

来源：https://stackoverflow.com/questions/20219885/forcing-a-gui-update-inside-of-a-thread-jslider-updates