public class Test {

	private static boolean full = false;

	public static void main(String[] args) {
		Display display = new Display();
		Shell shell = new Shell(display);
		shell.setSize(200, 100);
		shell.open();

		ProgressBar bar = new ProgressBar(shell, SWT.SMOOTH);
		bar.setBounds(30, 10, 100, 30);
		bar.setMinimum(0);
		bar.setMaximum(50);

		new Thread(new Runnable() {

			@Override
			public void run() {

				// For ever and ever...
				while (true) {
					// Update UI & set progress bar to 0
					Display.getDefault().asyncExec(new Runnable() {

						@Override
						public void run() {
							// Some additional UI updates ...

							full = false;
							bar.setSelection(0);
						}
					});

					// Until progress bar isn't full...
					while (!full) {

						// Sleep
						try {
							Thread.sleep(100);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}

						// Increment progress bar
						Display.getDefault().syncExec(new Runnable() {
							@Override
							public void run() {
								if (bar.getSelection() >= bar.getMaximum()) {
									full = true;
									return;
								}

								bar.setSelection(bar.getSelection() + 1);
							}
						});
					}
				}

			}
		}).start();

		while (!shell.isDisposed()) {
			if (!display.readAndDispatch())
				display.sleep();
		}
		display.dispose();
	}
}