Android aSyncTask and starting another activity

I've got this inner class as part of an application which doesn't accept changes in orientation (it makes more sense in landscape orientation).

  private class initialDBQuery extends AsyncTask<SQLiteDatabase, Void, Cursor> {

    @Override
    protected Cursor doInBackground(SQLiteDatabase... params) {
        final SQLiteDatabase mDatabase = params[0];
        mCursor = mDatabase.rawQuery("SELECT * FROM database", null);
        return mCursor;
    }

    @Override
    protected void onPostExecute(Cursor c){

        ParentActivity.this.mCursor = mCursor; 
        ParentActivity.this.updateQuery();
        mDatabase.close(); //Close database connection AS开发者_如何学PythonAP
    }

    // can use UI thread here
    protected void onPreExecute() {
        ParentActivity.this.mAnimalPager = null;
        Toast.makeText(ParentActivity.this.getBaseContext(), "Loading Database...", Toast.LENGTH_SHORT).show();
    }
} 

My main UI has a number of buttons which lead to different activities, the function of which is to provide search criteria via intents to the main activity (ParentActivity) which will then perform a search. the rest of the main activity is a viewpager which dependsonthe cursor returned from the AsyncTask (the update of this is working fine).

My problem is that: with this code i, I press one of the onscreen buttons (launch another activity) while the asynctask is running then I get the error "Unable to pause activity".

what are the further steps I need to take to deal with the running of the AsyncTask when the app pauses?

thanks, m

The problem I was experiencing here was actually to do with the viewpager I have on the main activity.

As the AsyncTask was creating a cursor for the PagerAdapter i wasn't setting the adapter until it had finished. There is a known problem with ViewPagers and activity onPause when an adapter has not been set (see here).

To overcome this I modified my adapter to return 0 when there is no cursor available to the adapter:

public int getCount() {
    // return the size of the cursor if it has been instantiated; 
    return (mCursor !=null) ? mCursor.getCount() : 0 ; 
}

and added a setCurrentCursor method to the adapter. This way I was able to set the adapter up and bind it to the viewpager in onCreate and then add the cursor to the adapter when it became available from the ASyncTask;

    public void setCurrentCursor(Cursor cu){
    this.mCursor = cu; 
    this.notifyDataSetChanged();
}

Now all I have to do is call adapter.setCurrentCursor in the onPostExecute method of the ASyncTask passing in the created cursor.

Hope this helps.

Thanks, m

first try to cancel the asynctask and then start another activity may be that work for you.