NfcA
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()Disable I/O operations to the tag from this |
| Unit |
connect()Enable I/O operations to the tag from this |
| static NfcA! |
Get an instance of |
| ByteArray! |
getAtqa()Return the ATQA/SENS_RES bytes from tag discovery. |
| Int |
Return the maximum number of bytes that can be sent with |
| Short |
getSak()Return the SAK/SEL_RES bytes from tag discovery. |
| Tag! |
getTag()Get the |
| Int |
Get the current |
| Boolean |
Helper to indicate if I/O operations should be possible. |
| Unit |
setTimeout(timeout: Int)Set the |
| ByteArray! |
transceive(data: ByteArray!)Send raw NFC-A commands to the tag and receive the response. |
Public methods
close
fun close(): Unit
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 android.Manifest.permission#NFC permission.
| 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
fun connect(): Unit
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 android.Manifest.permission#NFC permission.
| Exceptions | |
|---|---|
android.nfc.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
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
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
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
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
fun getTag(): Tag!
Get the Tag object backing this TagTechnology object.
| Return | |
|---|---|
Tag! |
the Tag backing this TagTechnology object. |
getTimeout
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
fun isConnected(): Boolean
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.
| Return | |
|---|---|
Boolean |
true if I/O operations should be possible |
setTimeout
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
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 | |
|---|---|
android.nfc.TagLostException |
if the tag leaves the field |
java.io.IOException |
if there is an I/O failure, or this operation is canceled |