java.lang.Object | |
↳ | android.nfc.NdefMessage |
Represents an immutable NDEF Message.
NDEF (NFC Data Exchange Format) is a light-weight binary format, used to encapsulate typed data. It is specified by the NFC Forum, for transmission and storage with NFC, however it is transport agnostic.
NDEF defines messages and records. An NDEF Record contains typed data, such as MIME-type media, a URI, or a custom application payload. An NDEF Message is a container for one or more NDEF Records.
When an Android device receives an NDEF Message (for example by reading an NFC tag) it processes it through a dispatch mechanism to determine an activity to launch. The type of the first record in the message has special importance for message dispatch, so design this record carefully.
Use NdefMessage(byte[])
to construct an NDEF Message from
binary data, or NdefMessage(NdefRecord[])
to
construct from one or more NdefRecord
s.
NdefMessage
and NdefRecord
implementations are
always available, even on Android devices that do not have NFC hardware.
NdefRecord
s are intended to be immutable (and thread-safe),
however they may contain mutable fields. So take care not to modify
mutable fields passed into constructors, or modify mutable fields
obtained by getter methods, unless such modification is explicitly
marked as safe.
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Inherited Constants | |||||||||||
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From interface
android.os.Parcelable
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Fields | |||||||||||
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CREATOR |
Public Constructors | |||||||||||
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Construct an NDEF Message by parsing raw bytes.
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Construct an NDEF Message from one or more NDEF Records.
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Construct an NDEF Message from one or more NDEF Records.
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Public Methods | |||||||||||
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Describe the kinds of special objects contained in this Parcelable's
marshalled representation.
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Returns true if the specified NDEF Message contains
identical NDEF Records.
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Return the length of this NDEF Message if it is written to a byte array
with
toByteArray() . | |||||||||||
Get the NDEF Records inside this NDEF Message.
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Returns an integer hash code for this object.
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Return this NDEF Message as raw bytes.
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Returns a string containing a concise, human-readable description of this
object.
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Flatten this object in to a Parcel.
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Inherited Methods | |||||||||||
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From class
java.lang.Object
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From interface
android.os.Parcelable
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Construct an NDEF Message by parsing raw bytes.
Strict validation of the NDEF binary structure is performed: there must be at least one record, every record flag must be correct, and the total length of the message must match the length of the input data.
This parser can handle chunked records, and converts them
into logical NdefRecord
s within the message.
Once the input data has been parsed to one or more logical
records, basic validation of the tnf, type, id, and payload fields
of each record is performed, as per the documentation on
on NdefRecord(short, byte[], byte[], byte[])
If either strict validation of the binary format fails, or
basic validation during record construction fails, a
FormatException
is thrown
Deep inspection of the type, id and payload fields of
each record is not performed, so it is possible to parse input
that has a valid binary format and confirms to the basic
validation requirements of
NdefRecord(short, byte[], byte[], byte[])
,
but fails more strict requirements as specified by the
NFC Forum.
It is safe to re-use the data byte array after construction: this constructor will make an internal copy of all necessary fields.
data | raw bytes to parse |
---|
FormatException | if the data cannot be parsed |
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Construct an NDEF Message from one or more NDEF Records.
record | first record (mandatory) |
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records | additional records (optional) |
Construct an NDEF Message from one or more NDEF Records.
records | one or more records |
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Describe the kinds of special objects contained in this Parcelable's marshalled representation.
Returns true if the specified NDEF Message contains identical NDEF Records.
obj | the object to compare this instance with. |
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true
if the specified object is equal to this Object
; false
otherwise.Return the length of this NDEF Message if it is written to a byte array
with toByteArray()
.
An NDEF Message can be formatted to bytes in different ways
depending on chunking, SR, and ID flags, so the length returned
by this method may not be equal to the length of the original
byte array used to construct this NDEF Message. However it will
always be equal to the length of the byte array produced by
toByteArray()
.
toByteArray()
Get the NDEF Records inside this NDEF Message.
An NdefMessage
always has one or more NDEF Records: so the
following code to retrieve the first record is always safe
(no need to check for null or array length >= 1):
NdefRecord firstRecord = ndefMessage.getRecords()[0];
Returns an integer hash code for this object. By contract, any two
objects for which equals(Object)
returns true
must return
the same hash code value. This means that subclasses of Object
usually override both methods or neither method.
Note that hash values must not change over time unless information used in equals comparisons also changes.
See Writing a correct
hashCode
method
if you intend implementing your own hashCode
method.
Return this NDEF Message as raw bytes.
The NDEF Message is formatted as per the NDEF 1.0 specification, and the byte array is suitable for network transmission or storage in an NFC Forum NDEF compatible tag.
This method will not chunk any records, and will always use the short record (SR) format and omit the identifier field when possible.
Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:
getClass().getName() + '@' + Integer.toHexString(hashCode())
See Writing a useful
toString
method
if you intend implementing your own toString
method.
Flatten this object in to a Parcel.
dest | The Parcel in which the object should be written. |
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flags | Additional flags about how the object should be written.
May be 0 or PARCELABLE_WRITE_RETURN_VALUE .
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