SharedPreferencesBackupHelper

open class SharedPreferencesBackupHelper : BackupHelper

A helper class that can be used in conjunction with android.app.backup.BackupAgentHelper to manage the backup of android.content.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 android.app.backup.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 android.content.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 <code><a docref="android.content.Context$getSharedPreferences(kotlin.String, kotlin.Int)">Context#getSharedPreferences(String, int)</a></code>.
      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

SharedPreferencesBackupHelper(
    context: Context!, 
    vararg prefGroups: String!)

Public methods

open fun performBackup(
    oldState: ParcelFileDescriptor!, 
    data: BackupDataOutput!, 
    newState: ParcelFileDescriptor!
): Unit

open fun restoreEntity(data: BackupDataInputStream!): Unit

open fun writeNewStateDescription(fd: ParcelFileDescriptor!): Unit