Added in API level 10

TagTechnology

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Kotlin |Java

interface TagTechnology : Closeable

android.nfc.tech.TagTechnology

Known Direct Subclasses IsoDep, MifareClassic, MifareUltralight, Ndef, NdefFormatable, NfcA, NfcB, NfcBarcode, NfcF, NfcV IsoDep Provides access to ISO-DEP (ISO 14443-4) properties and I/O operations on a Tag. MifareClassic Provides access to MIFARE Classic properties and I/O operations on a Tag. MifareUltralight Provides access to MIFARE Ultralight properties and I/O operations on a Tag. Ndef Provides access to NDEF content and operations on a Tag. NdefFormatable Provide access to NDEF format operations on a Tag. NfcA Provides access to NFC-A (ISO 14443-3A) properties and I/O operations on a Tag. NfcB Provides access to NFC-B (ISO 14443-3B) properties and I/O operations on a Tag. NfcBarcode Provides access to tags containing just a barcode. NfcF Provides access to NFC-F (JIS 6319-4) properties and I/O operations on a Tag. NfcV Provides access to NFC-V (ISO 15693) properties and I/O operations on a Tag.

is an interface to a technology in a Tag

Obtain a TagTechnology implementation by calling the static method get() on the implementation class.

NFC tags are based on a number of independently developed technologies and offer a wide range of capabilities. The TagTechnology implementations provide access to these different technologies and capabilities. Some sub-classes map to technology specification (for example NfcA, IsoDep, others map to pseudo-technologies or capabilities (for example Ndef, NdefFormatable).

It is mandatory for all Android NFC devices to provide the following TagTechnology implementations.

• NfcA (also known as ISO 14443-3A)
• NfcB (also known as ISO 14443-3B)
• NfcF (also known as JIS 6319-4)
• NfcV (also known as ISO 15693)
• IsoDep
• Ndef on NFC Forum Type 1, Type 2, Type 3 or Type 4 compliant tags

It is optional for Android NFC devices to provide the following TagTechnology implementations. If it is not provided, the Android device will never enumerate that class via Tag.getTechList.

• MifareClassic
• MifareUltralight
• NfcBarcode
• NdefFormatable must only be enumerated on tags for which this Android device is capable of formatting. Proprietary knowledge is often required to format a tag to make it NDEF compatible.

TagTechnology implementations provide methods that fall into two classes: cached getters and I/O operations.

Cached getters

These methods (usually prefixed by get or is) return properties of the tag, as determined at discovery time. These methods will never block or cause RF activity, and do not require connect to have been called. They also never update, for example if a property is changed by an I/O operation with a tag then the cached getter will still return the result from tag discovery time.

I/O operations

I/O operations may require RF activity, and may block. They have the following semantics.

• connect must be called before using any other I/O operation.
• close must be called after completing I/O operations with a TagTechnology, and it will cancel all other blocked I/O operations on other threads (including connect with IOException.
• Only one TagTechnology can be connected at a time. Other calls to connect will return IOException.
• I/O operations may block, and should never be called on the main application thread.

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

Summary

Public methods
abstract Unit	close() Disable I/O operations to the tag from this TagTechnology object, and release resources.
abstract Unit	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.

Public methods

close

Added in API level 10

abstract 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

See Also

• #connect()

connect

Added in API level 10

abstract 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
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

See Also

getTag

Added in API level 10

abstract fun getTag(): Tag!

Get the Tag object backing this TagTechnology object.

Return
Tag!	the Tag backing this TagTechnology object.

isConnected

Added in API level 10

abstract 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