Android: content observer's “onChange()” method is called multiple times

Question

I am using a content observer for content://sms. I am writing all the messages to a text file in SD card. But the onChange() method in the content

Answer 1

You need to override deliverSelfNotifications() to return true.

class ObserverSms extends ContentObserver {
private Context mContext;

public ObserverSms(Context context, Handler handler) {
    super(handler);
    mContext = context;
}

@Override
public boolean deliverSelfNotifications() {
    return true;
}

@Override
public void onChange(boolean selfChange) {
    super.onChange(selfChange);
    MyLog.logDebugInConsole(TAG, "Sms Database Changed");
}
}

Answer 2

The onChange() event is called once for each column that changes (i.e. "body" or "address") - thus the multiple calls. The easiest way to only process the data once is to store the value of the "_id" column, see if it has changed on the next iteration and then ignore.

cur.getColumnIndex("_id")

See example here: Sms ContentObserver onChange() fires multiple times

Answer 3

Vivek, please ensure that you unregister your content observer any time you leave the activity e.g. in onDestroy() method, call unregisterContentObserver(). Hope this help ! (in my case it worked)

Answer 4

Try this to avoid multiple execution of onChange()

private Context context;
    private static int initialPos;
    private static final String TAG = "SMSContentObserver";
    private static final Uri uriSMS = Uri.parse("content://sms/sent");

    public SmsObserver(Handler handler, Context ctx) {
        super(handler);
        context = ctx;
        trackMeData = context.getSharedPreferences("LockedSIM", 0);
        initialPos = getLastMsgId();

    }

    @Override
    public void onChange(boolean selfChange) {
        super.onChange(selfChange);
        queryLastSentSMS();
    }

    public int getLastMsgId() {

        Cursor cur = context.getContentResolver().query(uriSMS, null, null, null, null);
        cur.moveToFirst();
        int lastMsgId = cur.getInt(cur.getColumnIndex("_id"));
        Log.i(TAG, "Last sent message id: " + String.valueOf(lastMsgId));
        return lastMsgId;
    }

    protected void queryLastSentSMS() {

        new Thread(new Runnable() {

            @Override
            public void run() {
                Cursor cur =
                    context.getContentResolver().query(uriSMS, null, null, null, null);

                if (cur.moveToNext()) {



                    try {

                        String body = cur.getString(cur.getColumnIndex("body"));

                        if (initialPos != getLastMsgId()) {

                            String receiver = cur.getString(cur.getColumnIndex("address"));
                            Log.i("account", myDeviceId);
                            Log.i("date", day + "-" + month + "-" + year + " "
                                + hour + ":" + minute + ":" + seconde);
                            Log.i("sender", myTelephoneNumber);
                            Log.i("receiver", receiver );


                            // Then, set initialPos to the current position.
                            initialPos = getLastMsgId();

                            sendsmstoph(receiver, body);
                        }
                    } catch (Exception e) {
                        // Treat exception here
                    }
                }
                cur.close();
            }
        }).start();

    }