Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Methods](https://developer.android.com/reference/android/app/backup/BackupDataInput#pubmethods) \| [Protected Methods](https://developer.android.com/reference/android/app/backup/BackupDataInput#promethods) \| [Inherited Methods](https://developer.android.com/reference/android/app/backup/BackupDataInput#inhmethods)

# BackupDataInput

*** ** * ** ***


`
public


class
BackupDataInput
`


`

extends https://developer.android.com/reference/java/lang/Object


`

`


`

|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | android.app.backup.BackupDataInput |

<br />

*** ** * ** ***

Provides the structured interface through which a `https://developer.android.com/reference/android/app/backup/BackupAgent` reads
information from the backup data set, via its
`https://developer.android.com/reference/android/app/backup/BackupAgent#onRestore(android.app.backup.BackupDataInput,%20int,%20android.os.ParcelFileDescriptor)`
method. The data is presented as a set of "entities," each
representing one named record as previously stored by the agent's
`https://developer.android.com/reference/android/app/backup/BackupAgent#onBackup(android.os.ParcelFileDescriptor,%20android.app.backup.BackupDataOutput,%20android.os.ParcelFileDescriptor)` implementation. An entity is composed of a descriptive header plus a
byte array that holds the raw data saved in the remote backup.


The agent must consume every entity in the data stream, otherwise the
restored state of the application will be incomplete.

### Example


A typical
`https://developer.android.com/reference/android/app/backup/BackupAgent#onRestore(android.app.backup.BackupDataInput,%20int,%20android.os.ParcelFileDescriptor)` implementation might be structured something like this:

```
public void onRestore(BackupDataInput data, int appVersionCode,
                      ParcelFileDescriptor newState) {
    while (data.readNextHeader()) {
        String key = data.getKey();
        int dataSize = data.getDataSize();

        if (key.equals(MY_BACKUP_KEY_ONE)) {
            // process this kind of record here
            byte[] buffer = new byte[dataSize];
            data.readEntityData(buffer, 0, dataSize); // reads the entire entity at once

            // now 'buffer' holds the raw data and can be processed however
            // the agent wishes
            processBackupKeyOne(buffer);
        } else if (key.equals(MY_BACKUP_KEY_TO_IGNORE) {
            // a key we recognize but wish to discard
            data.skipEntityData();
        } // ... etc.
   }
}
```

<br />

## Summary

| ### Public methods ||
|---|---|
| ` int` | ` https://developer.android.com/reference/android/app/backup/BackupDataInput#getDataSize()() ` Report the size in bytes of the data associated with the current entity in the restore stream. |
| ` https://developer.android.com/reference/java/lang/String` | ` https://developer.android.com/reference/android/app/backup/BackupDataInput#getKey()() ` Report the key associated with the current entity in the restore stream |
| ` int` | ` https://developer.android.com/reference/android/app/backup/BackupDataInput#readEntityData(byte[],%20int,%20int)(byte[] data, int offset, int size) ` Read a record's raw data from the restore stream. |
| ` boolean` | ` https://developer.android.com/reference/android/app/backup/BackupDataInput#readNextHeader()() ` Extract the next entity header from the restore stream. |
| ` void` | ` https://developer.android.com/reference/android/app/backup/BackupDataInput#skipEntityData()() ` Consume the current entity's data without extracting it into a buffer for further processing. |

| ### Protected methods ||
|---|---|
| ` void` | ` https://developer.android.com/reference/android/app/backup/BackupDataInput#finalize()() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. |

### Inherited methods

From class `

https://developer.android.com/reference/java/lang/Object

` `


https://developer.android.com/reference/java/lang/Object` `
https://developer.android.com/reference/java/lang/Object#clone()()
`

Creates and returns a copy of this object.


`


boolean` `
https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj)
`

Indicates whether some other object is "equal to" this one.


`


void` `
https://developer.android.com/reference/java/lang/Object#finalize()()
`

Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.


`


final

https://developer.android.com/reference/java/lang/Class<?>` `
https://developer.android.com/reference/java/lang/Object#getClass()()
`

Returns the runtime class of this `Object`.


`


int` `
https://developer.android.com/reference/java/lang/Object#hashCode()()
`

Returns a hash code value for the object.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#notify()()
`

Wakes up a single thread that is waiting on this object's
monitor.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#notifyAll()()
`

Wakes up all threads that are waiting on this object's monitor.


`


https://developer.android.com/reference/java/lang/String` `
https://developer.android.com/reference/java/lang/Object#toString()()
`

Returns a string representation of the object.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#wait(long,%20int)(long timeoutMillis, int nanos)
`

Causes the current thread to wait until it is awakened, typically
by being *notified* or *interrupted*, or until a
certain amount of real time has elapsed.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#wait(long)(long timeoutMillis)
`

Causes the current thread to wait until it is awakened, typically
by being *notified* or *interrupted*, or until a
certain amount of real time has elapsed.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#wait()()
`

Causes the current thread to wait until it is awakened, typically
by being *notified* or *interrupted*.


## Public methods

### getDataSize

Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public int getDataSize ()
```

Report the size in bytes of the data associated with the current entity in the
restore stream.

<br />

| Returns ||
|---|---|
| `int` | The size of the record's raw data, in bytes <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalStateException` | if the next record header has not yet been read |

### getKey

Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public String getKey ()
```

Report the key associated with the current entity in the restore stream

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/String` | the current entity's key string <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalStateException` | if the next record header has not yet been read |

### readEntityData

Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public int readEntityData (byte[] data, 
                int offset, 
                int size)
```

Read a record's raw data from the restore stream. The record's header must first
have been processed by the `https://developer.android.com/reference/android/app/backup/BackupDataInput#readNextHeader()` method. Multiple calls to
this method may be made in order to process the data in chunks; not all of it
must be read in a single call. Once all of the raw data for the current entity
has been read, further calls to this method will simply return zero.

<br />

| Parameters ||
|---|---|
| `data` | `byte`: An allocated byte array of at least 'size' bytes <br /> |
| `offset` | `int`: Offset within the 'data' array at which the data will be placed when read from the stream <br /> |
| `size` | `int`: The number of bytes to read in this pass <br /> |

| Returns ||
|---|---|
| `int` | The number of bytes of data read. Once all of the data for this entity has been read, further calls to this method will return zero. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an error occurred when trying to read the restore data stream |

### readNextHeader

Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean readNextHeader ()
```

Extract the next entity header from the restore stream. After this method
return success, the `https://developer.android.com/reference/android/app/backup/BackupDataInput#getKey()` and `https://developer.android.com/reference/android/app/backup/BackupDataInput#getDataSize()` methods can
be used to inspect the entity that is now available for processing.

<br />

| Returns ||
|---|---|
| `boolean` | `true` when there is an entity ready for consumption from the restore stream, `false` if the restore stream has been fully consumed. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an error occurred while reading the restore stream |

### skipEntityData

Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public void skipEntityData ()
```

Consume the current entity's data without extracting it into a buffer
for further processing. This allows a `https://developer.android.com/reference/android/app/backup/BackupAgent` to
efficiently discard obsolete or otherwise uninteresting records during the
restore operation.

<br />

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an error occurred when trying to read the restore data stream |

## Protected methods

### finalize

Added in [API level 8](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected void finalize ()
```

Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
A subclass overrides the `finalize` method to dispose of
system resources or to perform other cleanup.


The general contract of `finalize` is that it is invoked
if and when the Java virtual
machine has determined that there is no longer any
means by which this object can be accessed by any thread that has
not yet died, except as a result of an action taken by the
finalization of some other object or class which is ready to be
finalized. The `finalize` method may take any action, including
making this object available again to other threads; the usual purpose
of `finalize`, however, is to perform cleanup actions before
the object is irrevocably discarded. For example, the finalize method
for an object that represents an input/output connection might perform
explicit I/O transactions to break the connection before the object is
permanently discarded.


The `finalize` method of class `Object` performs no
special action; it simply returns normally. Subclasses of
`Object` may override this definition.


The Java programming language does not guarantee which thread will
invoke the `finalize` method for any given object. It is
guaranteed, however, that the thread that invokes finalize will not
be holding any user-visible synchronization locks when finalize is
invoked. If an uncaught exception is thrown by the finalize method,
the exception is ignored and finalization of that object terminates.


After the `finalize` method has been invoked for an object, no
further action is taken until the Java virtual machine has again
determined that there is no longer any means by which this object can
be accessed by any thread that has not yet died, including possible
actions by other objects or classes which are ready to be finalized,
at which point the object may be discarded.


The `finalize` method is never invoked more than once by a Java
virtual machine for any given object.


Any exception thrown by the `finalize` method causes
the finalization of this object to be halted, but is otherwise
ignored.

<br />

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/Throwable` |   |