Android: Updating the UI from an adapter inside a While Loop - multithreading

Question

I'm using a GridView to display a list of words in a 4-column table. The getView method of my custom adapter checks the width of the word and shrinks it if it doesn't fit. It does this using a recursive check that keeps scaling the text down until it fits.
private void shrinkText(final TextView wv, final String word) {
wv.setTextSize(defaultTextSize);
new Thread(new Runnable() {
#Override
public void run() {
while (wv.getWidth()>0 && wv.getPaint().measureText(word) > wv.getWidth()) {
Logg.d("word too big. Shrink from " + wv.getTextSize()/density + " to " + (wv.getTextSize()/density-1.0f));
wv.setTextSize(wv.getTextSize() / density - 1.0f);
}
}
}).start();
}
Because I'm using a while loop, I am using a new thread to protect against ANR in the unlikely event of an infinite loop. Here's the weird thing: sometimes it works great. And then sometimes I get the following error:
09-26 14:25:31.389 6427-7765/com.myapp.debug E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-7789
Process: com.myapp.debug, PID: 6427
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
I tried putting the setTextSize inside a runOnUiThread statement, but I can't get it to work inside the adapter. Ultimately I just want this to work. I think my options are:
Keep the while loop in the UI thread and somehow safeguard it (how?)
Move the setTextSize call to the UI thread (how?)
Something else?
Thanks for your help!
UPDATE: based on Rustam's answer, I used wv.post to write to the UI. However the need to use the while loop meant that setTextSize had to be done in the same thread as the while condition itself. I switched from evaluating the TextView.getTextSize to the Paint.getTextSize, since I could set the Paint's text size without impacting the UI, and therefore inside the offshoot thread. Jerry-rigged, but it seems to work.
private void shrinkText(final TextView wv, final String word) {
wv.setTextSize(defaultTextSize);
final Paint mPaint = new Paint(wv.getPaint());
new Thread(new Runnable() {
#Override
public void run() {
while (wv.getWidth()>0 && mPaint.measureText(word) > wv.getWidth()) {
Logg.d("word too big. Shrink from " + mPaint.getTextSize()/density + " to " + (mPaint.getTextSize()/density-1.0f));
mPaint.setTextSize(mPaint.getTextSize() - 1.0f);
}
if (wv.getWidth()>0 && wv.getPaint().measureText(word) > wv.getWidth()) {
wv.post(new Runnable() {
#Override
public void run() {
Logg.d(word + " final size=" + mPaint.getTextSize() / density);
wv.setTextSize(mPaint.getTextSize() / density);
}
});
}
}
}).start();
}

Answer 1

try to update like this:
private void shrinkText(final TextView wv, final String word) {
wv.setTextSize(defaultTextSize);
new Thread(new Runnable() {
#Override
public void run() {
while (wv.getWidth()>0 && wv.getPaint().measureText(word) > wv.getWidth()) {
Logg.d("word too big. Shrink from " + wv.getTextSize()/density + " to " + (wv.getTextSize()/density-1.0f));
wv.post(new Runnable() {
public void run() {
wv.setTextSize(wv.getTextSize() / density - 1.0f);
}
});
}
}).start();
}