AD2

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Data Storage in Android

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Data Storage in Android
 Preferences
 Files
 SQLite
 Network

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Preference
A way of data persistence in Android that stores data in form of
key value pair like user specific setting, endpoint url, the
security access token etc.
Android stores shared preference settings
as XML file under:-
data/data/packagename/shared_prefs/
packagename_preferences.xml.

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Preference
once you uninstall the
application
once you clear
application data (through
Settings)
The data is lost when you perform any one following task:-

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Commonly used Shared Preferences
 ListPreference
 CheckBoxPreference
 EditTextPreference

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Preference
Creating preferences:-
The Preferences Activity screen is defined in the preferences.xml
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android"
android:key=“pref_screen“….>
<CheckBoxPreference
android:key=“checkbox_pref“…. />
<ListPreference
android:key=“list_pref“…./>
<EditTextPreference
android:key=“edit_pref”…./>
</PreferenceScreen>

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Create the Preferences Activity
public class AppPreferences extends PreferenceActivity
{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref);
}
}
Preference

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Preference
To read the preferences values
SharedPreferences sp =
PreferenceManager.getDefaultSharedPreferences(getBaseContext());
String strUserName = sp.getString("username", “ABC");
boolean bAppUpdates = sp.getBoolean("applicationUpdates",false);
String downloadType = sp.getString("downloadType","1");

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Internal storage
 It is private to your application and other applications
cannot access them (nor can the user)
 When the app uninstalls, these files are removed.
External storage
 External storage such as SD card can also store application data.
 There's no security enforced upon files you save to the external
storage.
 All applications can read and write files placed on the external
storage and the user can remove them for this they need Read
and Write permission.
Internal & External
Storage

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SQLite DB
SQLite is an Open Source database which supports standard
relational database features like SQL syntax, transaction etc.
It is embedded into every Android
device.
Database is by default saved in the
directory
DATA/data/APP_NAME/databases/FILENA
ME.

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SQLite DB
Necessary classes for working with databases:-
 SQLiteHelper
 SQLiteDataBase
 Cursor

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Content Provider

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Content Provider
An Android component that supplies data from one app to another on
request.
A content provider can use different ways to store its data and the data can be
stored in a database, infiles, or even over a network.

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Content Provider

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Content Provider
Creating content provider
 Create a content provider class that extends the contentproviderbaseclass.
 Define your content provider uri address.
 Create your own database to keep the content.
 Implement content provider queries.
 Register your content provider in menifest file.

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Demo
Security and Packages

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Demo
Talking to the Server