I tried to implement the following code to handle screen orientation changes.
****DataBaseUpdateService.java****
public class DataBaseUpdateService extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Updatetask Task = new Updatetask(this.getApplicationContext());
if(Task.getStatus() == AsyncTask.Status.PENDING){
Task.execute();};
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onResume() {
super.onResume();
}
}
==========================================================================
****Androidmanifest.xml****
<activity
android:name=".DataBaseUpdateService"
android:configChanges="keyboardHidden|orientation"/>
Those codes work perfectly with android 3.x or lower. However, it does not work properly for android 4.x.
Do you have any idea what the problem is??
Solution 1 – Think twice if you really need an AsyncTask.
Solution 2 – Put the AsyncTask in a Fragment.
Solution 3 – Lock the screen orientation
Solution 4 – Prevent the Activity from being recreated.
Reference:http://androidresearch.wordpress.com/2013/05/10/dealing-with-asynctask-and-screen-orientation/
..... the problem happens because the activity recreated when configuration changes,like orientation change etc. You can lock the orientation change in the onPreExecuted() method of asyntask and unlock it in the onPostExecuted() method.
import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.content.res.Configuration;
import android.os.AsyncTask;
import android.widget.Button;
import android.widget.ProgressBar;
public class MyAsyncTask extends AsyncTask<Void, Integer, Void> {
private Context context;
private ProgressBar progressBar;
private Button button;
public MyAsyncTask(ProgressBar progressBar,Context context,Button button){
this.context=context;
this.progressBar=progressBar;
this.button=button;
}
private void lockScreenOrientation() {
int currentOrientation =context.getResources().getConfiguration().orientation;
if (currentOrientation == Configuration.ORIENTATION_PORTRAIT) {
((Activity)
context).setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
} else {
((Activity) context).
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
}
private void unlockScreenOrientation() {
((Activity) context).
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
progressBar.setMax(100);
button.setEnabled(false);
lockScreenOrientation();
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
for(int i=0;i<=100;i++){
try {
Thread.sleep(200);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
publishProgress(i);
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
progressBar.setProgress(values[0]);
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
button.setEnabled(true);
unlockScreenOrientation();
}
}