SwingWorker Example

From EggeWiki

Here's a basic example of how to use a SwingWorker for a long running background task.

Idle

Running

package swingworker;
 
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
 
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
 
import org.jdesktop.swingworker.SwingWorker;
 
public class LuckyNumber extends JFrame implements ActionListener {
	private static final long serialVersionUID = 4276832367310733568L;
	private JLabel label;
	private JButton cancel;
	private JButton start;
	private SwingWorker<?,?> worker;
	private JTextField textField;
 
	public LuckyNumber() {
		JPanel panel = new JPanel();
		panel.setLayout(new GridLayout(2, 1));
 
		JPanel buttons = new JPanel(new FlowLayout());
		start = new JButton("Start");
		start.addActionListener(this);
		start.setDefaultCapable(true);
		buttons.add(start);
		cancel = new JButton("Cancel");
		cancel.setEnabled(false);
		cancel.addActionListener(this);
		buttons.add(cancel);
		panel.add(buttons);
 
		ImageIcon image;
		if (getClass().getResourceAsStream("/swingworker/spinner.gif") != null)
			image = new ImageIcon("swingworker/spinner.gif");
		else
			image = new ImageIcon("http://www.me.com/my/shared_1b/en/images/spinners/spinner_32px_f3f5f5.gif");
 
		label = new JLabel(image);
		JPanel answer = new JPanel(new GridLayout(1, 2));
		textField = new JTextField("");
		answer.add(textField);
		answer.add(label);
		label.setVisible(false);
		panel.add(answer);
 
		setTitle("Lucky number generator");
		setPreferredSize(new Dimension(300, 100));
		getContentPane().setLayout(new BorderLayout());
		getContentPane().add(panel);
 
	}
 
	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {
			public void run() {
				LuckyNumber luckyNumber = new LuckyNumber();
				luckyNumber.pack();
				luckyNumber.setVisible(true);
				luckyNumber.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
			}
		});
	}
 
	public void actionPerformed(ActionEvent e) {
		if (e.getSource() == start) {
			start.setEnabled(false);
			textField.setText("");
			worker = new NumberWorker();
			worker.execute();
			label.setVisible(true);
			cancel.setEnabled(true);
		} else if (e.getSource() == cancel) {
			cancel();
		}
 
	}
 
	@Override
	public void dispose() {
		cancel();
		super.dispose();
	}
 
	private void cancel() {
		start.setEnabled(true);
		label.setVisible(false);
		cancel.setEnabled(false);
		if (worker != null) {
			worker.cancel(true);
			worker = null;
		}
 
	}
 
	private class NumberWorker extends SwingWorker<String, Object> {
 
		private Random r = new Random();
 
		@Override
		protected String doInBackground() throws Exception {
			long s = System.currentTimeMillis();
			while (System.currentTimeMillis() - s < 5000 && !Thread.currentThread().isInterrupted()) {
				r.nextInt();
			}
			return String.valueOf(r.nextInt(10) + 1);
		}
 
		@Override
		protected void done() {
			try {
				textField.setText(get());
				LuckyNumber.this.worker = null;
				LuckyNumber.this.cancel();
			} catch (Exception ignore) {
			}
		}
	}
 
}