I have an Activity which has a ListView as its content View. I need to
call Activity.setContentView after a short asynchronous delay from
when Activity.onCreate is called (because there is a delay loading a
network resource needed to fully construct the ListView's
ArrayAdapter). In this case, it seems that the ListView won't enter
trackball mode or receive focus, unless I first touch the screen.
I have tried to distill this to a minimal example pasted below. There
is a comment at the top of the class explaining how the two variables
control the examples behavior.
Any ideas on how I can re-enable trackball mode, without requiring the
user to first touch the screen?
package foobar.androidtest;
import android.app.*;
import android.os.*;
import android.widget.*;
//
// With the settings SYNCHRONOUS=false and SLEEP=3000, then
// when the ListView is displayed, the first item won't be
// highlighted, and the trackball doesn't work.
//
// However, if you either change SYNCHRONOUS=true or SLEEP=0
// then when the ListView is displayed, the first item is
// highlighted, and the trackball works just fine.
//
public class AndroidTest extends Activity {
private static final boolean SYNCHRONOUS = false;
private static final int SLEEP = 3000;
public void onCreate(Bundle bundle) {
super.onCreate(bundle);
if(SYNCHRONOUS) {
doSetContentView();
}
else {
final Handler mainThreadHandler = new Handler();
Runnable backgroundThreadRunnable = new Runnable() {
public void run() {
optionalSleep();
Runnable mainThreadRunnable = new Runnable() {
public void run() {
doSetContentView();
}
};
mainThreadHandler.post(mainThreadRunnable);
}
};
Thread backgroundThread = new Thread
(backgroundThreadRunnable);
backgroundThread.start();
}
}
private void doSetContentView() {
String[] strings = new String[] {
"SYNCHRONOUS: " + SYNCHRONOUS,
"SLEEP: " + SLEEP,
"third item",
"fourth item",
"etc..."
};
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(
this, android.R.layout.simple_list_item_1, strings);
ListView listView = new ListView(this);
listView.setAdapter(arrayAdapter);
setContentView(listView);
}
private void optionalSleep() {
if(SLEEP > 0) {
try {
Thread.sleep(SLEEP);
}
catch(InterruptedException interruptedException) {
throw new RuntimeException(interruptedException);
}
}
}
}
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