Added in API level 10

Summary: Methods | Inherited Methods

NfcA

Kotlin |Java

public final class NfcA
extends Object implements TagTechnology

java.lang.Object
↳	android.nfc.tech.NfcA

Provides access to NFC-A (ISO 14443-3A) properties and I/O operations on a Tag.

Acquire a NfcA object using get(Tag).

The primary NFC-A I/O operation is transceive(byte). Applications must implement their own protocol stack on top of transceive(byte).

Note: Methods that perform I/O operations require the Manifest.permission.NFC permission.

Summary

Public methods
`void`	`close()` Disable I/O operations to the tag from this `TagTechnology` object, and release resources.
`void`	`connect()` Enable I/O operations to the tag from this `TagTechnology` object.
`static NfcA`	`get(Tag tag)` Get an instance of `NfcA` for the given tag.
`byte[]`	`getAtqa()` Return the ATQA/SENS_RES bytes from tag discovery.
`int`	`getMaxTransceiveLength()` Return the maximum number of bytes that can be sent with `transceive(byte)`.
`short`	`getSak()` Return the SAK/SEL_RES bytes from tag discovery.
`Tag`	`getTag()` Get the `Tag` object backing this `TagTechnology` object.
`int`	`getTimeout()` Get the current `transceive(byte)` timeout in milliseconds.
`boolean`	`isConnected()` Helper to indicate if I/O operations should be possible.
`void`	`setTimeout(int timeout)` Set the `transceive(byte)` timeout in milliseconds.
`byte[]`	`transceive(byte[] data)` Send raw NFC-A commands to the tag and receive the response.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(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`	`wait(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`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          android.nfc.tech.TagTechnology

`abstract void`	`close()` Disable I/O operations to the tag from this `TagTechnology` object, and release resources.
`abstract void`	`connect()` Enable I/O operations to the tag from this `TagTechnology` object.
`abstract Tag`	`getTag()` Get the `Tag` object backing this `TagTechnology` object.
`abstract boolean`	`isConnected()` Helper to indicate if I/O operations should be possible.

From interface


        
          java.io.Closeable


      close()

Closes this stream and releases any system resources associated with it.

From interface


        
          java.lang.AutoCloseable


      close()

Closes this resource, relinquishing any underlying resources.

Public methods

close

Added in API level 10

public void close ()

Disable I/O operations to the tag from this TagTechnology object, and release resources.

Also causes all blocked I/O operations on other thread to be canceled and return with IOException.

Requires the Manifest.permission.NFC permission.

Throws
`IOException`

connect

Added in API level 10

public void connect ()

Enable I/O operations to the tag from this TagTechnology object.

May cause RF activity and may block. Must not be called from the main application thread. A blocked call will be canceled with IOException by calling close() from another thread.

Only one TagTechnology object can be connected to a Tag at a time.

Applications must call close() when I/O operations are complete.

Requires the Manifest.permission.NFC permission.

Throws
`IOException`

get

Added in API level 10

public static NfcA get (Tag tag)

Get an instance of NfcA for the given tag.

Returns null if NfcA was not enumerated in Tag.getTechList. This indicates the tag does not support NFC-A.

Does not cause any RF activity and does not block.

Parameters
`tag`	`Tag`: an NFC-A compatible tag

Returns
`NfcA`	NFC-A object

getAtqa

Added in API level 10

public byte[] getAtqa ()

Return the ATQA/SENS_RES bytes from tag discovery.

Does not cause any RF activity and does not block.

Returns
`byte[]`	ATQA/SENS_RES bytes

getMaxTransceiveLength

Added in API level 14

public int getMaxTransceiveLength ()

Return the maximum number of bytes that can be sent with transceive(byte).

Returns
`int`	the maximum number of bytes that can be sent with `transceive(byte)`.

getSak

Added in API level 10

public short getSak ()

Return the SAK/SEL_RES bytes from tag discovery.

Does not cause any RF activity and does not block.

Returns
`short`	SAK bytes

getTag

Added in API level 10

public Tag getTag ()

Get the Tag object backing this TagTechnology object.

Returns
`Tag`	the `Tag` backing this `TagTechnology` object.

getTimeout

Added in API level 14

public int getTimeout ()

Get the current transceive(byte) timeout in milliseconds.

Requires the Manifest.permission.NFC permission.

Returns
`int`	timeout value in milliseconds

Throws
`SecurityException`	if the tag object is reused after the tag has left the field

isConnected

Added in API level 10

public boolean isConnected ()

Helper to indicate if I/O operations should be possible.

Returns true if connect() has completed, and close() has not been called, and the Tag is not known to be out of range.

Does not cause RF activity, and does not block.

Returns
`boolean`	true if I/O operations should be possible

setTimeout

Added in API level 14

public void setTimeout (int timeout)

Set the transceive(byte) timeout in milliseconds.

The timeout only applies to transceive(byte) on this object, and is reset to a default value when close() is called.

Setting a longer timeout may be useful when performing transactions that require a long processing time on the tag such as key generation.

Requires the Manifest.permission.NFC permission.

Parameters
`timeout`	`int`: timeout value in milliseconds

Throws
`SecurityException`	if the tag object is reused after the tag has left the field

transceive

Added in API level 10

public byte[] transceive (byte[] data)

Send raw NFC-A commands to the tag and receive the response.

Applications must not append the EoD (CRC) to the payload, it will be automatically calculated.

Applications must only send commands that are complete bytes, for example a SENS_REQ is not possible (these are used to manage tag polling and initialization).

Use getMaxTransceiveLength() to retrieve the maximum number of bytes that can be sent with transceive(byte).

This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with IOException if close() is called from another thread.

Requires the Manifest.permission.NFC permission.

Parameters
`data`	`byte`: bytes to send

Returns
`byte[]`	bytes received in response

Throws
	if the tag leaves the field
`IOException`	if there is an I/O failure, or this operation is canceled