SwingWorker

Problem: Perform a time-consuming task, likely to freeze the GUI.
Solution: Use the SwingWorker class, part of java 6.
Example:

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private Document doc; ... JButton button = new JButton("Load"); button.addActionListener(new ActionListener() {     public void actionPerformed(ActionEvent e) {         SwingWorker<Document, Void> worker =             new SwingWorker<Document, Void>() {                 @Override public Document doInBackground() {                     return load();                 }                 @Override public void done() {                     try {                         doc = get();                     } catch (Exception e) {                         e.printStackTrace();                     }                 }             };         worker.execute();    } });