Question

I have run into a problem that may interest many (beginners). Let me show you the code:

startButton.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            startButton.setVisibility(View.GONE);
            if (!started) {
                started = true;
                timer.start();
                information.append("Start 1\n");
                tester1.start();
                if (cores >= 2) {
                    information.append("Start 2\n");
                    tester2.start();
                }
                if (cores >= 3) {
                    information.append("Start 3\n");
                    tester3.start();
                }
                if (cores >= 4) {
                    information.append("Start 4\n");
                    tester4.start();
                }

            }
        }
    });

timer, and all testers are threads previously declared.
information is a TextView.

The problem is that when I run the app, the textview changes after the threads finish, even if the threads take 10 seconds to finish. This does happen on the emulator (android 2.3) and on a real (android 4.0) device. The odd thing is, the threads do start at roughly the same time.

Answer 1

You must update any UI components from main thread.

For example

runOnUiThread(new Runnable() {
    public void run() {
        someTextView.setText(someResultVariable);
    }
});