title: Android: content observer's "onChange()" method is called multiple times
body: <p>I am using a content observer for <code>content://sms</code>. I am writing all the messages to a text file in SD card. But the <code>onChange()</code> method in the content observer is called multiple times and the same message is written multiple times to the text file. How to avoid this? Also I want to know if having the content observer will slow down the phone.</p>