This tutorials shows how to use self signed certificates in Android application. This tutorials aimed only for testing and development, since you should never allow self signed certificates in released application.
Android SharedPreferences is a cool way to store user preferences to a file. All of the work is handled by the SharedPreferences class and as a bonus the class creates a file that is human readable.
Google Guava includes useful tools for splitting and joining String. This tutorial shows how they are used.
Mobile device may lose its network connection any time. This short example shows how to check if the Android device has a working connection.
This tutorial shows how to convert InputStream content easily to a String object.