Android :: User Thread To Update UI But Dialog Still Come After Task

I'm trying to learn AsyncTask and Thread but Thread first. I am trying to display a Dialog before "DoSomeTask()" but seems like the Dialog always come after DoSomeTask(). Did I do something wrong here?

--- code---
@Override public void onClick(View v) {
// TODO Auto-generated method stub mainProcessing();
DoSomeTask(); } private void mainProcessing() {
Thread thread = new Thread(null, doBackgroundThreadProcessing, "Background");
thread.start(); }
private Runnable doBackgroundThreadProcessing = new Runnable() {
public void run() { backgroundThreadProcessing();
} };
private void backgroundThreadProcessing() {
handler.post(doUpdateGUI);
} private Runnable doUpdateGUI = new Runnable() {
public void run() { updateGUI();
} };
private void updateGUI() {
final ProgressDialog dialog = new ProgressDialog(CloseVault.this);
dialog.setMessage("Please wait...");
dialog.show();
}