give delay in showing the controls - eclipse-plugin

Question

I would like to add the button controls in a timely manner.
That means, after the shell opened, it should start placing the buttons one by one
in a 1 second delay. I wrote the program,however it does not work. all the buttons
are visible only after all the controls are placed. Some kind of refresh issue I guess.
Following is my code.
public class DelayAddingComponentsExample {
public static void main(String[] args) {
Display display = new Display();
final Shell shell = new Shell(display);
shell.setSize(200, 200);
shell.setLayout(new FillLayout(SWT.VERTICAL));
addAutomatically(shell);
// removeAutomatically(shell);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
public static void addAutomatically(final Shell shell) {
for (int i = 0; i < 5; i++) {
final Button button = new Button(shell, SWT.NONE);
button.setText("Button" + i);
button.setVisible(false);
}
shell.getDisplay().timerExec(0, new Runnable() {
#Override
public void run() {
for (int i = 0; i < 5; i++) {
try {
Thread.sleep(500);
final Button button = new Button(shell, SWT.NONE);
button.setText("Button" + i);
button.setVisible(true);
shell.pack();
shell.layout(true);
shell.redraw();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
});
}
public static void removeAutomatically(final Shell shell) {
for (int i = 0; i < 5; i++) {
final Button button = new Button(shell, SWT.NONE);
button.setText("Button" + i);
shell.layout(true);
}
shell.getDisplay().timerExec(0, new Runnable() {
#Override
public void run() {
Control[] controls = shell.getChildren();
for (Control control : controls) {
try {
Thread.sleep(500);
control.dispose();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
});
}
}

Answer 1

The Runnable given to timerExec runs in the UI thread. So the Thread.sleep calls you are making are blocking the UI thread - it is vital that you never block this thread. Never call Thread.sleep in the UI thread.
You must do each step using a separate timeExec call and use the delay parameter of the timerExec call to specify how long to wait.
So
shell.getDisplay().timerExec(500, new Runnable() {
#Override
public void run()
{
// TODO code for the first button only
// Schedule next update
shell.getDisplay().timerExec(500, .... code for second button);
}
});
Runs the Runnable after 500 millseconds, the Runnable should just do the first step and then call timerExec again to schedule the next step.