Added in API level 9

NdefMessage


class NdefMessage : Parcelable
kotlin.Any
   ↳ 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(android.nfc.NdefRecord[]) to construct from one or more NdefRecords.

NdefMessage and NdefRecord implementations are always available, even on Android devices that do not have NFC hardware.

NdefRecords 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.

Summary

Inherited constants
Public constructors

Construct an NDEF Message by parsing raw bytes.

NdefMessage(record: NdefRecord!, vararg records: NdefRecord!)

Construct an NDEF Message from one or more NDEF Records.

Construct an NDEF Message from one or more NDEF Records.

Public methods
Int

Boolean
equals(other: Any?)

Returns true if the specified NDEF Message contains identical NDEF Records.

Int

Return the length of this NDEF Message if it is written to a byte array with toByteArray.

Array<NdefRecord!>!

Get the NDEF Records inside this NDEF Message.

Int

ByteArray!

Return this NDEF Message as raw bytes.

String

Unit
writeToParcel(dest: Parcel, flags: Int)

Properties
static Parcelable.Creator<NdefMessage!>

Public constructors

NdefMessage

Added in API level 9
NdefMessage(data: ByteArray!)

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 NdefRecords 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#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#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.

Parameters
data ByteArray!: raw bytes to parse
Exceptions
android.nfc.FormatException if the data cannot be parsed

NdefMessage

Added in API level 16
NdefMessage(
    record: NdefRecord!,
    vararg records: NdefRecord!)

Construct an NDEF Message from one or more NDEF Records.

Parameters
record NdefRecord!: first record (mandatory)
records NdefRecord!: additional records (optional)

NdefMessage

Added in API level 9
NdefMessage(records: Array<NdefRecord!>!)

Construct an NDEF Message from one or more NDEF Records.

Parameters
records Array<NdefRecord!>!: one or more records

Public methods

describeContents

Added in API level 9
fun describeContents(): Int
Return
Int a bitmask indicating the set of special object types marshaled by this Parcelable object instance. Value is either 0 or android.os.Parcelable#CONTENTS_FILE_DESCRIPTOR

equals

Added in API level 9
fun equals(other: Any?): Boolean

Returns true if the specified NDEF Message contains identical NDEF Records.

Parameters
obj This value may be null.
Return
Boolean true if this object is the same as the obj argument; false otherwise.

getByteArrayLength

Added in API level 16
fun getByteArrayLength(): Int

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.

Return
Int length of this NDEF Message when written to bytes with toByteArray

See Also

getRecords

Added in API level 9
fun getRecords(): Array<NdefRecord!>!

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];
  
Return
Array<NdefRecord!>! array of one or more NDEF records.

hashCode

Added in API level 9
fun hashCode(): Int
Return
Int a hash code value for this object.

toByteArray

Added in API level 9
fun toByteArray(): ByteArray!

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.

Return
ByteArray! NDEF Message in binary format

toString

Added in API level 9
fun toString(): String
Return
String a string representation of the object.

writeToParcel

Added in API level 9
fun writeToParcel(
    dest: Parcel,
    flags: Int
): Unit
Parameters
dest Parcel: The Parcel in which the object should be written. This value cannot be null.
flags Int: Additional flags about how the object should be written. May be 0 or PARCELABLE_WRITE_RETURN_VALUE. Value is either 0 or a combination of android.os.Parcelable#PARCELABLE_WRITE_RETURN_VALUE, and android.os.Parcelable.PARCELABLE_ELIDE_DUPLICATES

Properties

CREATOR

Added in API level 9
static val CREATOR: Parcelable.Creator<NdefMessage!>