NfcA

Kotlin |Java

class NfcA : TagTechnology

kotlin.Any
↳	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.

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

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

Summary

Public methods
Unit	`close()`
Unit	`connect()`
static NfcA!	`get(tag: Tag!)` Get an instance of `NfcA` for the given tag.
ByteArray!	`getAtqa()` Return the ATQA/SENS_RES bytes from tag discovery.
Int	`getMaxTransceiveLength()` Return the maximum number of bytes that can be sent with `transceive`.
Short	`getSak()` Return the SAK/SEL_RES bytes from tag discovery.
Tag!	`getTag()`
Int	`getTimeout()` Get the current `transceive` timeout in milliseconds.
Boolean	`isConnected()`
Unit	`setTimeout(timeout: Int)` Set the `transceive` timeout in milliseconds.
ByteArray!	`transceive(data: ByteArray!)` Send raw NFC-A commands to the tag and receive the response.

Public methods

close

Added in API level 10

fun close(): Unit

Exceptions
`java.lang.Exception`	if this resource cannot be closed
`java.io.IOException`	if an I/O error occurs
`java.lang.SecurityException`	if the tag object is reused after the tag has left the field

connect

Added in API level 10

fun connect(): Unit

Exceptions
`TagLostException`	if the tag leaves the field
`java.io.IOException`	if there is an I/O failure, or connect is canceled
`java.lang.SecurityException`	if the tag object is reused after the tag has left the field

get

Added in API level 10

static fun get(tag: Tag!): NfcA!

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

Return
`NfcA!`	NFC-A object

getAtqa

Added in API level 10

fun getAtqa(): ByteArray!

Return the ATQA/SENS_RES bytes from tag discovery.

Does not cause any RF activity and does not block.

Return
`ByteArray!`	ATQA/SENS_RES bytes

getMaxTransceiveLength

Added in API level 14

fun getMaxTransceiveLength(): Int

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

Return
`Int`	the maximum number of bytes that can be sent with `transceive`.

getSak

Added in API level 10

fun getSak(): Short

Return the SAK/SEL_RES bytes from tag discovery.

Does not cause any RF activity and does not block.

Return
`Short`	SAK bytes

getTag

Added in API level 10

fun getTag(): Tag!

Return
`Tag!`	the `Tag` backing this `TagTechnology` object.

getTimeout

Added in API level 14

fun getTimeout(): Int

Get the current transceive timeout in milliseconds.

Requires the android.Manifest.permission#NFC permission.

Return
`Int`	timeout value in milliseconds

Exceptions
`java.lang.SecurityException`	if the tag object is reused after the tag has left the field

isConnected

Added in API level 10

fun isConnected(): Boolean

Return
`Boolean`	true if I/O operations should be possible

setTimeout

Added in API level 14

fun setTimeout(timeout: Int): Unit

Set the transceive timeout in milliseconds.

The timeout only applies to transceive 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 android.Manifest.permission#NFC permission.

Parameters
`timeout`	Int: timeout value in milliseconds

Exceptions
`java.lang.SecurityException`	if the tag object is reused after the tag has left the field

transceive

Added in API level 10

fun transceive(data: ByteArray!): ByteArray!

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.

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 android.Manifest.permission#NFC permission.

Parameters
`data`	ByteArray!: bytes to send

Return
`ByteArray!`	bytes received in response

Exceptions
`TagLostException`	if the tag leaves the field
`java.io.IOException`	if there is an I/O failure, or this operation is canceled