{"id":346,"date":"2011-01-24T23:14:00","date_gmt":"2011-01-24T23:14:00","guid":{"rendered":"http:\/\/www.javacodegeeks.com\/2012\/10\/android-quick-preferences-tutorial.html"},"modified":"2019-12-02T16:32:45","modified_gmt":"2019-12-02T14:32:45","slug":"android-quick-preferences-tutorial","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2011\/01\/android-quick-preferences-tutorial.html","title":{"rendered":"Android Quick Preferences Tutorial"},"content":{"rendered":"
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When developing a mobile application, a common need that arises is the one of storing user’s preferences and using them when the application starts. Since this is a recurring need, Google has created a preferences framework for us. The provided mechanism allows us to show, save and manipulate user’s preferences very easily. Furthermore, the framework has support for automatic UI creation. What I mean is, that, by declaring the type of a user preference, a user interface for manipulating these preferences is automatically generated, without having to write a single line code. How does that sound for rapid application development?<\/p>\n

In order to make use of the preferences framework, the first step is to extend the PreferenceActivity<\/a> class. This is just a convenience class that derives from ListActivity<\/a> and allows to bootstrap the preferences UI from an XML file. Additionally, it automatically saves to SharedPreferences<\/a> behind the scenes. Don’t forget that SharedPreferences<\/a> is the interface responsible for accessing and modifying preference data and that we can manually manipulate it by calling the getSharedPreferences<\/a> method of an Activity<\/a>. In order to tie together our PreferenceActivity<\/a> class and the XML layout file, we use the addPreferencesFromResource<\/a> method. Thus, our onCreate<\/a> method is very simple and looks like this:<\/p>\n

...\n@Override\npublic void onCreate(Bundle savedInstanceState) {     \n    super.onCreate(savedInstanceState);        \n    addPreferencesFromResource(R.xml.preferences);        \n}\n...\n<\/pre>\n
[ulp id=’luHisu6VPL9Mt6IB’]<\/p>\n
This assumes that we have already created a file named \u201cpreferences.xml\u201d inside the \u201cres\/xml\u201d folder. Then, in run-time, the activity will inflate the given XML resource and add the preference hierarchy to the current preference hierarchy. This XML file has a specific format via which we define the types of the preferences. All types derive from the Preference<\/a> class, which represents the basic preference UI building block and provides the View<\/a> to be displayed in the activity and the association with a SharedPreferences<\/a> object to store\/retrieve the preference data. Here are some of the most common subclasses that you can directly use:<\/p>\n