Is there a good way to tell when an SMS gets read on Android?

I'm playing around with a small notification app. My basic requirements are: when an SMS comes in, turn on the LED. When it gets read, turn it off. The first part seems easy enough: I have a BroadcastReceiver with the following in my manifest:

<intent-filter>
    <action android:name="android.provider.Telephony.SMS_RECEIVED" />
</intent-filter>

However, the second part has proven more tricky. Currently, I have a service which starts up whenever a message comes in. It runs a TimerTask every 15 seconds which runs this code:

int count = 0;

Uri providerURI = Uri.parse( "content://sms" );
Cursor cursor = this.getContentResolver().query( providerURI, null, "read=0", null, null );

if( cursor != null ) {
    try {
        count = cursor.getCount();
    }
    finally {
        cursor.close();
    }
}

return count;

It seems to work well enough. When the count is 0, I cancel the TimerTask and stop the service. However, I'm concerned about battery life. Is there any sort of general notification for when the num开发者_StackOverflow社区ber of unread messages changes? Or any better way of doing this?

You can use ContentObserver. I suppose when a new message comes into sms inbox, you will get a notification (by content observer), on the other hand, when a sms has been read, it will be removed from inbox, and also you will get another notification.

ps, Use ContentObserver observing on content://sms/inbox