TagTechnology

Class Overview

TagTechnology 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 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 NFC permission.

Summary

Public Methods
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.

[Expand] Inherited Methods
From interface java.io.Closeable abstract void close () Closes the object and release any system resources it holds.
From interface java.lang.AutoCloseable abstract void close () Closes the object and release any system resources it holds.