Added in API level 8

FileBackupHelper

open class FileBackupHelper : BackupHelper
kotlin.Any
   ↳ android.app.backup.FileBackupHelper

A helper class that can be used in conjunction with android.app.backup.BackupAgentHelper to manage the backup of a set of files. Whenever backup is performed, all files changed since the last backup will be saved in their entirety. When backup first occurs, every file in the list provided to FileBackupHelper will be backed up.

During restore, if the helper encounters data for a file that was not specified when the FileBackupHelper object was constructed, that data will be ignored.

Note: This should be used only with small configuration files, not large binary files.

Summary

Public constructors
FileBackupHelper(context: Context!, vararg files: String!)

Construct a helper to manage backup/restore of entire files within the application's data directory hierarchy.
Public methods
open Unit

Based on oldState, determine which of the files from the application's data directory need to be backed up, write them to the data stream, and fill in newState with the state as it exists now.
open Unit

Restore one record [representing a single file] from the restore dataset.
open Unit

Public constructors

FileBackupHelper

Added in API level 8
FileBackupHelper(
    context: Context!, 
    vararg files: String!)

Construct a helper to manage backup/restore of entire files within the application's data directory hierarchy.

Parameters
context Context!: The backup agent's Context object
files String!: A list of the files to be backed up or restored.

Public methods

performBackup

Added in API level 8
open fun performBackup(
    oldState: ParcelFileDescriptor!, 
    data: BackupDataOutput!, 
    newState: ParcelFileDescriptor!
): Unit

Based on oldState, determine which of the files from the application's data directory need to be backed up, write them to the data stream, and fill in newState with the state as it exists now. When oldState is null, all the files will be backed up.

This should only be called directly from within the BackupAgentHelper implementation. See android.app.backup.BackupAgent#onBackup(ParcelFileDescriptor, BackupDataOutput, ParcelFileDescriptor) for a description of parameter meanings.

Parameters
oldState ParcelFileDescriptor!: An open, read-only android.os.ParcelFileDescriptor pointing to the last backup state provided by the application. May be null, in which case no prior state is being provided and the application should perform a full backup.
data BackupDataOutput!: An open, read/write BackupDataOutput pointing to the backup data destination. Typically the application will use backup helper classes to write to this file.
newState ParcelFileDescriptor!: An open, read/write android.os.ParcelFileDescriptor pointing to an empty file. The application should record the final backup state here after writing the requested data to the data output stream.

restoreEntity

Added in API level 8
open fun restoreEntity(data: BackupDataInputStream!): Unit

Restore one record [representing a single file] from the restore dataset.

This should only be called directly from within the BackupAgentHelper implementation.

Parameters
data BackupDataInputStream!: An open BackupDataInputStream from which the backup data can be read.

writeNewStateDescription

Added in API level 8
open fun writeNewStateDescription(fd: ParcelFileDescriptor!): Unit
Parameters
newState A android.os.ParcelFileDescriptor to which the new state will be written.