SharedPreferencesBackupHelper

public class SharedPreferencesBackupHelper
extends Object implements BackupHelper

A helper class that can be used in conjunction with BackupAgentHelper to manage the backup of SharedPreferences. Whenever a backup is performed, it will back up all named shared preferences that have changed since the last backup operation.

To use this class, the application's backup agent class should extend BackupAgentHelper. Then, in the agent's BackupAgent#onCreate() method, an instance of this class should be allocated and installed as a backup/restore handler within the BackupAgentHelper framework. For example, an agent supporting backup and restore for an application with two groups of SharedPreferences data might look something like this:

 import android.app.backup.BackupAgentHelper;
 import android.app.backup.SharedPreferencesBackupHelper;

 public class MyBackupAgent extends BackupAgentHelper {
     // The names of the SharedPreferences groups that the application maintains.  These
     // are the same strings that are passed to Context#getSharedPreferences(String, int).
     static final String PREFS_DISPLAY = "displayprefs";
     static final String PREFS_SCORES = "highscores";

     // An arbitrary string used within the BackupAgentHelper implementation to
     // identify the SharedPreferenceBackupHelper's data.
     static final String MY_PREFS_BACKUP_KEY = "myprefs";

     // Allocate a helper and install it.
     public void onCreate() {
         SharedPreferencesBackupHelper helper =
                 new SharedPreferencesBackupHelper(this, PREFS_DISPLAY, PREFS_SCORES);
         addHelper(MY_PREFS_BACKUP_KEY, helper);
     }
 }

No further implementation is needed; the BackupAgentHelper mechanism automatically dispatches the BackupAgent.onBackup() and BackupAgent.onRestore() callbacks to the SharedPreferencesBackupHelper as appropriate.

Summary

Public constructors

public SharedPreferencesBackupHelper (Context context, 
                String... prefGroups)

Public methods

public void performBackup (ParcelFileDescriptor oldState, 
                BackupDataOutput data, 
                ParcelFileDescriptor newState)

public void restoreEntity (BackupDataInputStream data)

public void writeNewStateDescription (ParcelFileDescriptor fd)