How can I keep executing work while a button is pressed?

问题

I want to keep executing work while a button is pressed, using Java. When the button is released, the work should stop. Something like this:

Button_is_pressed()
{
    for(int i=0;i<100;i++)
    {
        count=i;
        print "count"
    }
}

How might I achieve this?

回答1:

One way:

Add a ChangeListener to the JButton's ButtonModel
In this listener check the model's isPressed() method and turn on or off a Swing Timer depending on its state.
If you want a background process, then you can execute or cancel a SwingWorker in the same way.

An example of the former:

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

public class ButtonPressedEg {
   public static void main(String[] args) {
      int timerDelay = 100;
      final Timer timer = new Timer(timerDelay , new ActionListener() {

         @Override
         public void actionPerformed(ActionEvent e) {
            System.out.println("Button Pressed!");
         }
      });

      JButton button = new JButton("Press Me!");
      final ButtonModel bModel = button.getModel();
      bModel.addChangeListener(new ChangeListener() {

         @Override
         public void stateChanged(ChangeEvent cEvt) {
            if (bModel.isPressed() && !timer.isRunning()) {
               timer.start();
            } else if (!bModel.isPressed() && timer.isRunning()) {
               timer.stop();
            }
         }
      });

      JPanel panel = new JPanel();
      panel.add(button);


      JOptionPane.showMessageDialog(null, panel);

   }
}