Re: waiting threads until it gets value

On Sun, 27 Dec 2009, focode wrote:


It's not clear to me what you want. Is it that the application should
first display the main menu, and then if later on the GPRS verification
fails, it should switch to the error message and quit? In that case, you
don't necessarily need a wait - the code above will work, although it
could be even simpler:

public void check_gprs() {
  new Thread(this).start();
  switchDisplayable(null, getMainMenu());
}

public void run() {
  // try to download URL
  if (text.equals("error")) switchDisplayable(null, getPacketdatamissing());
}

That's all you need.

If you want the program to display the main menu and then wait until the
verification has finished, then you have a couple of options. The simplest
is actually to use join, not wait - join waits for another thread to
finish:

public void check_gprs() {
  Thread t = new Thread(this);
  t.start();
  switchDisplayable(null, getMainMenu());
  t.join();
}

If you want a real wait, it's like this:

private boolean verificationComplete = false;

public void check_gprs() {
  new Thread(this).start();
  switchDisplayable(null, getMainMenu());
  synchronized (this) {
  // you need to decide what to do with InterruptedException here
  while (!verificationComplete) wait();
  }
}

public void run() {
  // try to download URL
  if (text.equals("error")) switchDisplayable(null, getPacketdatamissing());
  synchronized (this) {
  verificationComplete = true;
  notifyAll();
  }
}

tom

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