Added in API level 10

Summary: Methods | Inherited Methods

IsoDep

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Kotlin |Java

public final class IsoDep
extends Object implements TagTechnology

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

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Provides access to ISO-DEP (ISO 14443-4) properties and I/O operations on a Tag.

Acquire an IsoDep object using get(Tag).

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

Tags that enumerate the IsoDep technology in Tag.getTechList will also enumerate NfcA or NfcB (since IsoDep builds on top of either of these).

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 IsoDep	get(Tag tag) Get an instance of IsoDep for the given tag.
byte[]	getHiLayerResponse() Return the higher layer response bytes for NfcB tags.
byte[]	getHistoricalBytes() Return the ISO-DEP historical bytes for NfcA tags.
int	getMaxTransceiveLength() Return the maximum number of bytes that can be sent with transceive(byte).
Tag	getTag() Get the Tag object backing this TagTechnology object.
int	getTimeout() Get the current timeout for transceive(byte) in milliseconds.
boolean	isConnected() Helper to indicate if I/O operations should be possible.
boolean	isExtendedLengthApduSupported() Standard APDUs have a 1-byte length field, allowing a maximum of 255 payload bytes, which results in a maximum APDU length of 261 bytes.
void	setTimeout(int timeout) Set the timeout of transceive(byte) in milliseconds.
byte[]	transceive(byte[] data) Send raw ISO-DEP data 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 abstract void close() Closes this stream and releases any system resources associated with it.
From interface java.lang.AutoCloseable abstract void 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 IsoDep get (Tag tag)

Get an instance of IsoDep for the given tag.

Does not cause any RF activity and does not block.

Returns null if IsoDep was not enumerated in Tag.getTechList. This indicates the tag does not support ISO-DEP.

Parameters
tag	Tag: an ISO-DEP compatible tag

Returns
IsoDep	ISO-DEP object

getHiLayerResponse

Added in API level 10

public byte[] getHiLayerResponse ()

Return the higher layer response bytes for NfcB tags.

Does not cause any RF activity and does not block.

The higher layer response bytes can be used to help identify a tag. They are present only on IsoDep tags that are based on NfcB RF technology. If this tag is not NfcB then null is returned.

In ISO 14443-4 terminology, the higher layer bytes are a subset of the ATTRIB response.

Returns
byte[]	ISO-DEP historical bytes, or null if this is not a NfcB tag

getHistoricalBytes

Added in API level 10

public byte[] getHistoricalBytes ()

Return the ISO-DEP historical bytes for NfcA tags.

Does not cause any RF activity and does not block.

The historical bytes can be used to help identify a tag. They are present only on IsoDep tags that are based on NfcA RF technology. If this tag is not NfcA then null is returned.

In ISO 14443-4 terminology, the historical bytes are a subset of the RATS response.

Returns
byte[]	ISO-DEP historical bytes, or null if this is not a NfcA tag

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).

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 timeout for transceive(byte) 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

isExtendedLengthApduSupported

Added in API level 16

public boolean isExtendedLengthApduSupported ()

Standard APDUs have a 1-byte length field, allowing a maximum of 255 payload bytes, which results in a maximum APDU length of 261 bytes.

Extended length APDUs have a 3-byte length field, allowing 65535 payload bytes.

Some NFC adapters, like the one used in the Nexus S and the Galaxy Nexus do not support extended length APDUs. They are expected to be well-supported in the future though. Use this method to check for extended length APDU support.

Returns
boolean	whether the NFC adapter on this device supports extended length APDUs.

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

setTimeout

Added in API level 10

public void setTimeout (int timeout)

Set the timeout of transceive(byte) in milliseconds.

The timeout only applies to ISO-DEP transceive(byte), 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 ISO-DEP data to the tag and receive the response.

Applications must only send the INF payload, and not the start of frame and end of frame indicators. Applications do not need to fragment the payload, it will be automatically fragmented and defragmented by transceive(byte) if it exceeds FSD/FSC limits.

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: command bytes to send, must not be null

Returns
byte[]	response bytes received, will not be null

Throws
	if the tag leaves the field
IOException	if there is an I/O failure, or this operation is canceled
SecurityException	if the tag object is reused after the tag has left the field