[android-developers] Question about SurfaceView and Threads

Hello, I recently started learning development for android (Game development to be specific). And I came across the question, to which I couldn't find an answer.

So my question would be why does this work?:

public class MainActivity extends Activity{

OurView v;

TextView textView;

Random random;

int num = 0;

public void onCreate(Bundle bundle){

super.onCreate(bundle);

v = new OurView(this);

setContentView(v);

textView = (TextView) findViewById(R.id.textView);

random = new Random();

}

protected void onResume(){

super.onResume();

v.resume();

}

public class OurView extends SurfaceView implements Runnable{

Thread t = null;

SurfaceHolder holder;

boolean isItOK = false;

public OurView(Context context) {

super(context);

holder = getHolder();

}

public void run() {

while(isItOK == true){

if(!holder.getSurface().isValid())

continue;

Canvas canvas = holder.lockCanvas();

canvas.drawARGB(random.nextInt(256), random.nextInt(256), random.nextInt(256), random.nextInt(256));

holder.unlockCanvasAndPost(canvas);

}

}

public void resume(){

isItOK = true;

t = new Thread(this);

t.start();

}

public void pause(){

isItOK = false;

while(true){

try{

t.join();

}catch(Exception e){

e.printStackTrace();

}

break;

}

}

}

}

but this doesn't:

public class MainActivity extends Activity{

OurView v;

TextView textView;

Random random;

int num = 0;

public void onCreate(Bundle bundle){

super.onCreate(bundle);

setContentView(R.layout.activity_main);

textView = (TextView) findViewById(R.id.textView);

random = new Random();

v = new OurView(this);

}

protected void onResume(){

super.onResume();

v.resume();

}

public class OurView extends SurfaceView implements Runnable{

Thread t = null;

SurfaceHolder holder;

boolean isItOK = false;

public OurView(Context context) {

super(context);

holder = getHolder();

}

public void run() {

while(isItOK == true){

num++;

textView.setText(num);

}

}

public void resume(){

isItOK = true;

t = new Thread(this);

t.start();

}

public void pause(){

isItOK = false;

while(true){

try{

t.join();

}catch(Exception e){

e.printStackTrace();

}

break;

}

}

}

}

All I did is changed content view. And in threads run() method I changed textView's text to "num" variable which is incremented in each while cycle...

I don't understand why this doesn't work. Why this doesn't use AsyncTask but uses Just plain old thread. I heard that android doesn't support plain old Java threads. I'm totally confused, and don't understand anything. Could someone please explain what's happening here?

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