What is the importance of a SwingWorker class in Java?\\n

A SwingWorker class enables us to perform an asynchronous task in a worker thread (such as a long-running task) then update Swing components from the Event Dispatch Thread (EDT) based on the task results. It was introduced in Java 1.6 Version.

SwingWorker class

• The java.swing.SwingWorker class is a task worker, which performs time-consuming tasks in the background.
• A SwingWorker instance interacts with 3 threads, Current thread, the Worker thread, and the Event Dispatch thread(EDT).
• The Current thread calls the execute() method to kick off the task to the background and returns immediately.
• The Worker thread executes our own version of the doInBackground() method continuously in the background.
• The Event Dispatch Thread (EDT) wakes up from time to time to notify us of what happened in the Worker thread.
• When doInBackground() is ended, the Event Dispatch Thread (EDT) notify us by call our version of the done() method.
• To publish intermediate values, we can call the publish(V) method in doInBackground(). The Event Dispatch Thread (EDT) notifies us by calling our version of the process(List) method.
• To update the progress property, we can call the setProgress(i) method in doInBackground(). The Event Dispatch Thread (EDT) notifies us by calling our version of a PropertyChangeListener class.
• The java.swing.JProgressbar class is a UI component designed to show the progress of a background task implemented as a SwingWorker instance.

Example

import java.awt.*; import java.awt.event.*;; import javax.swing.*; public class SwingWorkerTest {    public static void main(String[] args) {       EventQueue.invokeLater(new Runnable() {          @Override          public void run() {             JFrame frame = new JFrame();             JButton button = new JButton();             button.addActionListener(new ActionListener() {                @Override                public void actionPerformed(ActionEvent e) {                   new GUIWorker().execute();                }             });             button.setText("Click Me !!!");             frame.getContentPane().add(button);             frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);             frame.setLocationRelativeTo(null);             frame.setSize(350, 300);             frame.setVisible(true);          }       });    } } class GUIWorker extends SwingWorker {    private JFrame frame = new JFrame();    private JDialog dialog = new JDialog(frame, "Swingworker Test", true);    private JProgressBar progressBar = new JProgressBar();    public GUIWorker() {       progressBar.setString("Waiting on time");       progressBar.setStringPainted(true);       progressBar.setIndeterminate(true);       dialog.getContentPane().add(progressBar);       dialog.setSize(350, 300);       dialog.setModal(false);       dialog.setLocationRelativeTo(null);       dialog.setVisible(true);    }    @Override    protected Integer doInBackground() throws Exception {       System.out.println( "GUIWorker doInBackground()" );       Thread.sleep(10000);       return 0;    }    @Override    protected void done() {       System.out.println("done");       JLabel label = new JLabel("Task Complete");       dialog.getContentPane().remove(progressBar);       dialog.getContentPane().add(label);       dialog.getContentPane().validate();    } }

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