Keep time in android
<p>I'm trying to keep a timer in my android app. I need the start date of an event, and the end date. Both are triggered with a button, so  i've got those with:</p>

<pre><code>SimpleDateFormat sf = new SimpleDateFormat("yyyy-M-dd HH:mm:s");
Date theDate_start = new Date();
</code></pre>

<p>Is there a method to somehow get the delta date? This would be the easiest way in my opinion.</p>
