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javaswingevent-dispatch-thread

Should I allocate/create swing elements into EDT?

Should I create swing elements into EDT?

I got the concurrency problems with editing non thread-safe graphics elements, but I'm creating them, they aren't shown yet, and if they are a lot or they take some time to be allocated that would freeze the GUI, doesn't it?

Here an example where I use EDT to display but not to create my GUI structure:

public class Launcher {
    private final SwingWorker worker;
    private final JFrame frame;
    private final JLabel label;
    private final JProgressBar progressBar;

    public Launcher() {

        // init user interface
        frame = new JFrame();
        JPanel panel = new JPanel(new BorderLayout());
        label = new JLabel("Launching...", SwingConstants.CENTER);
        progressBar = new JProgressBar(0, 100);
        progressBar.setIndeterminate(true);
        panel.add(label, BorderLayout.CENTER);
        panel.add(progressBar, BorderLayout.PAGE_END);
        initUI(panel);
        worker = new LauncherWorker(this);
        worker.addPropertyChangeListener((PropertyChangeListener)this);
    }

    private void initUI(final Component panel) {
        if (!SwingUtilities.isEventDispatchThread()) {
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    DirectaChatLauncher.this.initUI(panel);
                } //run()
            });
            return;
        }
        Container contentPane = frame.getContentPane();
        contentPane.setLayout(new BorderLayout());
        contentPane.add(panel, BorderLayout.PAGE_END);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    @Override
    public void propertyChange(PropertyChangeEvent evt) {
        if ("progress".equals(evt.getPropertyName())) {
            int progress = (Integer) evt.getNewValue();
            progressBar.setValue(progress);
        }
    }

    private void setProgression(final String msg) {
        label.setText(msg);
    }

    class LauncherWorker extends SwingWorker<Boolean, String> {

        private final Launcher LAUNCHER;

        public LauncherWorker(Launcher launcher) {
            super();
            LAUNCHER = launcher;
        }

        @Override
        protected Boolean doInBackground() throws Exception {
            setProgress(0);
            publish("Started");
            ...
            setProgress(100);
            publish("Launched");
            Thread.sleep(1000);
            return Boolean.TRUE;
        }

        @Override
        protected void process(List<String> chunks) {
            LAUNCHER.setProgression(chunks.get(0));
        }

        @Override
        public void done() {
            LAUNCHER.done();
        }

    }
}

is it fine since the elements weren't displayed yet? or should I move all into initUI()?

Solution

  • In the Swing separable model architecture, a view component listens to its model. Because a view may respond arbitrarily to events generated by model updates, the corresponding model must also be updated on the EDT. You can mitigate latency via one of two basic approaches: