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added in API level 10

NfcF

public final class NfcF
extends Object implements TagTechnology

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


Provides access to NFC-F (JIS 6319-4) properties and I/O operations on a Tag.

Acquire a NfcF object using get(Tag).

The primary NFC-F 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 NfcF get(Tag tag)

Get an instance of NfcF for the given tag.

byte[] getManufacturer()

Return the Manufacturer bytes from tag discovery.

int getMaxTransceiveLength()

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

byte[] getSystemCode()

Return the System Code 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-F commands to the tag and receive the response.

Inherited methods

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 NfcF get (Tag tag)

Get an instance of NfcF for the given tag.

Returns null if NfcF was not enumerated in Tag.getTechList(). This indicates the tag does not support NFC-F.

Does not cause any RF activity and does not block.

Parameters
tag Tag: an NFC-F compatible tag

Returns
NfcF NFC-F object

getManufacturer

added in API level 10
public byte[] getManufacturer ()

Return the Manufacturer bytes from tag discovery.

Does not cause any RF activity and does not block.

Returns
byte[] Manufacturer 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[]).

getSystemCode

added in API level 10
public byte[] getSystemCode ()

Return the System Code bytes from tag discovery.

Does not cause any RF activity and does not block.

Returns
byte[] System Code 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

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

transceive

added in API level 10
public byte[] transceive (byte[] data)

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

Applications must not prefix the SoD (preamble and sync code) and/or append the EoD (CRC) to the payload, it will be automatically calculated.

A typical NFC-F frame for this method looks like:

 LENGTH (1 byte) --- CMD (1 byte) -- IDm (8 bytes) -- PARAMS (LENGTH - 10 bytes)
 

Use getMaxTransceiveLength() to retrieve the maximum amount 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