Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Ctors](https://developer.android.com/reference/android/hardware/usb/UsbRequest#pubctors) \| [Methods](https://developer.android.com/reference/android/hardware/usb/UsbRequest#pubmethods) \| [Protected Methods](https://developer.android.com/reference/android/hardware/usb/UsbRequest#promethods) \| [Inherited Methods](https://developer.android.com/reference/android/hardware/usb/UsbRequest#inhmethods)
# UsbRequest
*** ** * ** ***
[Kotlin](https://developer.android.com/reference/kotlin/android/hardware/usb/UsbRequest "View this page in Kotlin") \|Java
`
public
class
UsbRequest
`
`
extends https://developer.android.com/reference/java/lang/Object
`
`
`
|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | android.hardware.usb.UsbRequest |
*** ** * ** ***
A class representing USB request packet.
This can be used for both reading and writing data to or from a
`https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection`.
UsbRequests can be used to transfer data on bulk and interrupt endpoints.
Requests on bulk endpoints can be sent synchronously via `https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#bulkTransfer(android.hardware.usb.UsbEndpoint,%20byte[],%20int,%20int)`
or asynchronously via `https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer)` and `https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()`.
Requests on interrupt endpoints are only send and received asynchronously.
Requests on endpoint zero are not supported by this class;
use `https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#controlTransfer(int,%20int,%20int,%20int,%20byte[],%20int,%20int)` for endpoint zero requests instead.
## Summary
| ### Public constructors ||
|---|---|
| ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#UsbRequest()() ` |
| ### Public methods ||
|---|---|
| ` boolean` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#cancel()() ` Cancels a pending queue operation. |
| ` void` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#close()() ` Releases all resources related to this request. |
| ` https://developer.android.com/reference/java/lang/Object` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#getClientData()() ` Returns the client data for the request. |
| ` https://developer.android.com/reference/android/hardware/usb/UsbEndpoint` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#getEndpoint()() ` Returns the endpoint for the request, or null if the request is not opened. |
| ` boolean` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#initialize(android.hardware.usb.UsbDeviceConnection,%20android.hardware.usb.UsbEndpoint)(https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection connection, https://developer.android.com/reference/android/hardware/usb/UsbEndpoint endpoint) ` Initializes the request so it can read or write data on the given endpoint. |
| ` boolean` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer)(https://developer.android.com/reference/java/nio/ByteBuffer buffer) ` Queues the request to send or receive data on its endpoint. |
| ` boolean` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer,%20int)(https://developer.android.com/reference/java/nio/ByteBuffer buffer, int length) ` *This method was deprecated in API level 26. Use `https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer)` instead.* |
| ` void` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#setClientData(java.lang.Object)(https://developer.android.com/reference/java/lang/Object data) ` Sets the client data for the request. |
| ### Protected methods ||
|---|---|
| ` void` | ` https://developer.android.com/reference/android/hardware/usb/UsbRequest#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 constructors
### UsbRequest
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public UsbRequest ()
```
## Public methods
### cancel
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean cancel ()
```
Cancels a pending queue operation.
| Returns ||
|---|---|
| `boolean` | true if cancelling succeeded
|
### close
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void close ()
```
Releases all resources related to this request.
### getClientData
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Object getClientData ()
```
Returns the client data for the request.
This can be used in conjunction with `https://developer.android.com/reference/android/hardware/usb/UsbRequest#setClientData(java.lang.Object)`
to associate another object with this request, which can be useful for
maintaining state between calls to `https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer)` and
`https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()`
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Object` | the client data for the request
|
### getEndpoint
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public UsbEndpoint getEndpoint ()
```
Returns the endpoint for the request, or null if the request is not opened.
| Returns ||
|---|---|
| `https://developer.android.com/reference/android/hardware/usb/UsbEndpoint` | the request's endpoint
|
### initialize
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean initialize (UsbDeviceConnection connection,
UsbEndpoint endpoint)
```
Initializes the request so it can read or write data on the given endpoint.
Whether the request allows reading or writing depends on the direction of the endpoint.
| Parameters ||
|---|---|
| `connection` | `UsbDeviceConnection`
|
| `endpoint` | `UsbEndpoint`: the endpoint to be used for this request.
|
| Returns ||
|---|---|
| `boolean` | true if the request was successfully opened.
|
### queue
Added in [API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean queue (ByteBuffer buffer)
```
Queues the request to send or receive data on its endpoint.
For OUT endpoints, the remaining bytes of the buffer will be sent on the endpoint. For IN
endpoints, the endpoint will attempt to fill the remaining bytes of the buffer. If the
queueing operation is successful, return true. The result will be returned via
`https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()`
| Parameters ||
|---|---|
| `buffer` | `ByteBuffer`: the buffer containing the bytes to send, or the buffer to fill. The state of the buffer is undefined until the request is returned by `https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()`. If the request failed the buffer will be unchanged; if the request succeeded the position of the buffer is incremented by the number of bytes sent/received. Before `https://developer.android.com/reference/android/os/Build.VERSION_CODES#P`, a buffer of length larger than 16384 bytes would throw IllegalArgumentException. In API `https://developer.android.com/reference/android/os/Build.VERSION_CODES#P` and after, any size buffer is valid. This value may be `null`.
|
| Returns ||
|---|---|
| `boolean` | true if the queueing operation succeeded
|
### queue
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
Deprecated in [API level
26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean queue (ByteBuffer buffer,
int length)
```
**This method was deprecated
in API level 26.**
Use `https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer)` instead.
Queues the request to send or receive data on its endpoint.
For OUT endpoints, the given buffer data will be sent on the endpoint. For IN endpoints,
the endpoint will attempt to read the given number of bytes into the specified buffer. If the
queueing operation is successful, return true. The result will be returned via
`https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()`
| Parameters ||
|---|---|
| `buffer` | `ByteBuffer`: the buffer containing the bytes to write, or location to store the results of a read. Position and array offset will be ignored and assumed to be 0. Limit and capacity will be ignored. Once the request `https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()` the position will be set to the number of bytes read/written.
|
| `length` | `int`: number of bytes to read or write. Before `https://developer.android.com/reference/android/os/Build.VERSION_CODES#P`, a value larger than 16384 bytes would be truncated down to 16384. In API `https://developer.android.com/reference/android/os/Build.VERSION_CODES#P` and after, any value of length is valid.
|
| Returns ||
|---|---|
| `boolean` | true if the queueing operation succeeded
|
### setClientData
Added in [API level 12](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setClientData (Object data)
```
Sets the client data for the request.
This can be used in conjunction with `https://developer.android.com/reference/android/hardware/usb/UsbRequest#getClientData()`
to associate another object with this request, which can be useful for
maintaining state between calls to `https://developer.android.com/reference/android/hardware/usb/UsbRequest#queue(java.nio.ByteBuffer)` and
`https://developer.android.com/reference/android/hardware/usb/UsbDeviceConnection#requestWait()`
| Parameters ||
|---|---|
| `data` | `Object`: the client data for the request
|
## Protected methods
### finalize
Added in [API level 12](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.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/Throwable` | |