Preferences, File System and Menus

The work to do is to add a menu (also called an options menu) to the PermutationsReloaded application as shown in the picture. Choosing clear will erase everything on screen while choosing about will display a pop-up with some information about the app.

To create the menu, one should build one using the appropriate XML editor and override the onCreateOptionsMenu method of the activity. To handle clicks, the onOptionsItemSelected method will also need to be overriden.

Context menu

The second step is to add a context menu which opens when one long-presses on any of the permutations. The choices shown are “To uppercase” and “To lowercase” which are explicit enough.

The methods which are important here are onCreateContextMenu and onContextItemSelected as well as registerForContextMenu and unregisterForContextMenu.

Something noteworthy is that onCreateContextMenu is executed each time a context menu is shown (and not only once) and that one of its parameters is the view on which the long-press has been done.

Managing Preferences

The last enhancement to bring to the application is to allow the user to specify whether the last word entered should be remembered. If yes, the next time the application is started, the word should already appear in the EditText and the permutations shown.

To do that, a preference screen should be created using the XML editor, then a class derived from PreferenceActivity should be created and the onCreate method overriden. This new activity should be manually added to AndroidManifest.xml.

When this activity is launched (using, for example, startActivity), the Android framework will automatically store the preferences.

Finally, the application will have to be updated to store the word entered if the user has chosen to do so as well as restore that word when the application is resumed. The way to do that is to get a SharedPreference object from the PreferenceManager.

Accessing Files

Android applications can access files residing at three distinct places:

• Found in the application APK itself. This file is read-only as it is considered to be one of the static resources of the application. The work to do is to develop an application called Anagrams which given a word shows all the various anagrams of that word. Of course, this requires a dictionary and it will be stored in the APK. The key method to use here is openRawResource to get access to that dictionary.
• Found in flash memory. The second version of the application provides a simple menu (with load / save) which, depending on the item selected, either load or saves the anagrams found. This second version of the application loads and saves from flash memory.
• Found on the SD card. The third version of the application read and writes data on the SD card instead of using flash memory.