public interface TagTechnology
implements Closeable
android.nfc.tech.TagTechnology |
![]() |
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 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.
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.
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
. TagTechnology
can be connected at a time. Other calls to connect()
will return IOException
. Note: Methods that perform I/O operations require the NFC
permission.
Public methods |
|
---|---|
abstract void |
close() Disable I/O operations to the tag from this |
abstract void |
connect() Enable I/O operations to the tag from this |
abstract Tag |
getTag() Get the |
abstract boolean |
isConnected() Helper to indicate if I/O operations should be possible. |
Inherited methods |
|
---|---|
![]() java.io.Closeable
|
|
![]() java.lang.AutoCloseable
|
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 NFC
permission.
Throws | |
---|---|
IOException |
See also:
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 NFC
permission.
Throws | |
---|---|
|
if the tag leaves the field |
IOException |
if there is an I/O failure, or connect is canceled |
See also:
Tag getTag ()
Get the Tag
object backing this TagTechnology
object.
Returns | |
---|---|
Tag |
the Tag backing this TagTechnology object. |
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 |