Master Android from first principles and begin the journey toward your own successful Android applications!
Dear Reader,
First, welcome to the world of Android! We’re entering a new era of mobile application development, one marked by open platforms and open source, to take ‘walled gardens’ and make them green houses for any and all to participate in. Android is relatively easy for developers, and I believe that this innovation will help generate a large ecosystem of developers and consumers within a very short time. This means that budding developers such as yourself will have many opportunities to design and build your own applications and you’ll have a huge and hungry customer base.
Second, welcome to the book! Its purpose is to start you on your way with building Android applications, and to help you master the learning curve. Android is already a rich framework, comparable in many ways to the richness Android of desktop Java environments. This means that there is a lot of cool stuff for you to pick up along your journey in order to create the slickest, most useful apps Android you can imagine.
The source code for the code samples in this book is all available from the Apress site, so you can stay as hands-on and practical as you like while I introduce you to the core of Android, and invite you to experiment with the various classes and APIs we’ll be looking at. By the time you’ve finished this book, you’ll be creating your own Android applications and asking yourself what your next great application will be…!
Enjoy!
Mark Murphy
Getting What You Want
Getting What You Want
To get access to the preferences, you have three APIs to choose from:
• getPreferences() from within your Activity, to access activity-specific preferences
• getSharedPreferences() from within your Activity (or other application Context), to access application-level preferences
• getDefaultSharedPreferences(), on PreferencesManager, to get the shared preferences that work in concert with Android’s overall preference framework
The first two take a security-mode parameter — for now, pass in 0. The getSharedPreferences() method also takes a name of a set of preferences — getPreferences() effectively calls getSharedPreferences() with the activity’s class name as the preference set name. The getDefaultSharedPreferences() method takes the Context for the preferences (e.g., your Activity).
All of those methods return an instance of SharedPreferences, which offers a series of getters to access named preferences, returning a suitably typed result (e.g., getBoolean() to return a Boolean preference). The getters also take a default value, which is returned if there is no preference set under the specified key.
