Added in API level 1

Message

---

Kotlin |Java

class Message : Parcelable

kotlin.Any
↳	android.os.Message

Defines a message containing a description and arbitrary data object that can be sent to a Handler. This object contains two extra int fields and an extra object field that allow you to not do allocations in many cases.

While the constructor of Message is public, the best way to get one of these is to call #obtain or one of the android.os.Handler#obtainMessage methods, which will pull them from a pool of recycled objects.

Summary

Inherited constants

From class Parcelable Int CONTENTS_FILE_DESCRIPTOR Descriptor bit used with describeContents(): indicates that the Parcelable object's flattened representation includes a file descriptor. Int PARCELABLE_WRITE_RETURN_VALUE Flag for use with writeToParcel: the object being written is a return value, that is the result of a function such as "Parcelable someFunction()", "void someFunction(out Parcelable)", or "void someFunction(inout Parcelable)". Some implementations may want to release resources at this point.

Public constructors
Message() Constructor (but the preferred way to get a Message is to call Message.obtain()).

Public methods
Unit	copyFrom(o: Message!) Make this message like o.
Int	describeContents()
Runnable!	getCallback() Retrieve callback object that will execute when this message is handled.
Bundle!	getData() Obtains a Bundle of arbitrary data associated with this event, lazily creating it if necessary.
Handler!	getTarget() Retrieve the Handler implementation that will receive this message.
Long	getWhen() Return the targeted delivery time of this message, in milliseconds.
Boolean	isAsynchronous() Returns true if the message is asynchronous, meaning that it is not subject to Looper synchronization barriers.
static Message!	obtain() Return a new Message instance from the global pool.
static Message!	obtain(orig: Message!) Same as obtain(), but copies the values of an existing message (including its target) into the new one.
static Message!	obtain(h: Handler!) Same as obtain(), but sets the value for the target member on the Message returned.
static Message!	obtain(h: Handler!, callback: Runnable!) Same as obtain(android.os.Handler), but assigns a callback Runnable on the Message that is returned.
static Message!	obtain(h: Handler!, what: Int) Same as obtain(), but sets the values for both target and what members on the Message.
static Message!	obtain(h: Handler!, what: Int, obj: Any!) Same as obtain(), but sets the values of the target, what, and obj members.
static Message!	obtain(h: Handler!, what: Int, arg1: Int, arg2: Int) Same as obtain(), but sets the values of the target, what, arg1, and arg2 members.
static Message!	obtain(h: Handler!, what: Int, arg1: Int, arg2: Int, obj: Any!) Same as obtain(), but sets the values of the target, what, arg1, arg2, and obj members.
Bundle?	peekData() Like getData(), but does not lazily create the Bundle.
Unit	recycle() Return a Message instance to the global pool.
Unit	sendToTarget() Sends this Message to the Handler specified by getTarget.
Unit	setAsynchronous(async: Boolean) Sets whether the message is asynchronous, meaning that it is not subject to Looper synchronization barriers.
Unit	setData(data: Bundle!) Sets a Bundle of arbitrary data values.
Unit	setTarget(target: Handler!)
String	toString()
Unit	writeToParcel(dest: Parcel, flags: Int)

Properties
static Parcelable.Creator<Message!>	CREATOR
Int	arg1 arg1 and arg2 are lower-cost alternatives to using setData() if you only need to store a few integer values.
Int	arg2 arg1 and arg2 are lower-cost alternatives to using setData() if you only need to store a few integer values.
Any!	obj An arbitrary object to send to the recipient.
Messenger!	replyTo Optional Messenger where replies to this message can be sent.
Int	sendingUid Optional field indicating the uid that sent the message.
Int	what User-defined message code so that the recipient can identify what this message is about.

Public constructors

Message

Added in API level 1

Message()

Constructor (but the preferred way to get a Message is to call Message.obtain()).

Public methods

copyFrom

Added in API level 1

fun copyFrom(o: Message!): Unit

Make this message like o. Performs a shallow copy of the data field. Does not copy the linked list fields, nor the timestamp or target/callback of the original message.

describeContents

Added in API level 1

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

getCallback

Added in API level 1

fun getCallback(): Runnable!

Retrieve callback object that will execute when this message is handled. This object must implement Runnable. This is called by the target Handler that is receiving this Message to dispatch it. If not set, the message will be dispatched to the receiving Handler's Handler#handleMessage(Message).

getData

Added in API level 1

fun getData(): Bundle!

Obtains a Bundle of arbitrary data associated with this event, lazily creating it if necessary. Set this value by calling setData(android.os.Bundle). Note that when transferring data across processes via Messenger, you will need to set your ClassLoader on the Bundle via Bundle.setClassLoader() so that it can instantiate your objects when you retrieve them.

See Also

• #peekData()
• #setData(Bundle)

getTarget

Added in API level 1

fun getTarget(): Handler!

Retrieve the Handler implementation that will receive this message. The object must implement Handler.handleMessage(). Each Handler has its own name-space for message codes, so you do not need to worry about yours conflicting with other handlers.

getWhen

Added in API level 1

fun getWhen(): Long

Return the targeted delivery time of this message, in milliseconds.

isAsynchronous

Added in API level 22

fun isAsynchronous(): Boolean

Returns true if the message is asynchronous, meaning that it is not subject to Looper synchronization barriers.

Return
Boolean	True if the message is asynchronous.

See Also

• #setAsynchronous(boolean)

obtain

Added in API level 1

static fun obtain(): Message!

Return a new Message instance from the global pool. Allows us to avoid allocating new objects in many cases.

obtain

Added in API level 1

static fun obtain(orig: Message!): Message!

Same as obtain(), but copies the values of an existing message (including its target) into the new one.

Parameters
orig	Message!: Original message to copy.

Return
Message!	A Message object from the global pool.

obtain

Added in API level 1

static fun obtain(h: Handler!): Message!

Same as obtain(), but sets the value for the target member on the Message returned.

Parameters
h	Handler!: Handler to assign to the returned Message object's target member.

Return
Message!	A Message object from the global pool.

obtain

Added in API level 1

static fun obtain(
    h: Handler!, 
    callback: Runnable!
): Message!

Same as obtain(android.os.Handler), but assigns a callback Runnable on the Message that is returned.

Parameters
h	Handler!: Handler to assign to the returned Message object's target member.
callback	Runnable!: Runnable that will execute when the message is handled.

Return
Message!	A Message object from the global pool.

obtain

Added in API level 1

static fun obtain(
    h: Handler!, 
    what: Int
): Message!

Same as obtain(), but sets the values for both target and what members on the Message.

Parameters
h	Handler!: Value to assign to the target member.
what	Int: Value to assign to the what member.

Return
Message!	A Message object from the global pool.

obtain

Added in API level 1

static fun obtain(
    h: Handler!, 
    what: Int, 
    obj: Any!
): Message!

Same as obtain(), but sets the values of the target, what, and obj members.

Parameters
h	Handler!: The target value to set.
what	Int: The what value to set.
obj	Any!: The object method to set.

Return
Message!	A Message object from the global pool.

obtain

Added in API level 1

static fun obtain(
    h: Handler!, 
    what: Int, 
    arg1: Int, 
    arg2: Int
): Message!

Same as obtain(), but sets the values of the target, what, arg1, and arg2 members.

Parameters
h	Handler!: The target value to set.
what	Int: The what value to set.
arg1	Int: The arg1 value to set.
arg2	Int: The arg2 value to set.

Return
Message!	A Message object from the global pool.

obtain

Added in API level 1

static fun obtain(
    h: Handler!, 
    what: Int, 
    arg1: Int, 
    arg2: Int, 
    obj: Any!
): Message!

Same as obtain(), but sets the values of the target, what, arg1, arg2, and obj members.

Parameters
h	Handler!: The target value to set.
what	Int: The what value to set.
arg1	Int: The arg1 value to set.
arg2	Int: The arg2 value to set.
obj	Any!: The obj value to set.

Return
Message!	A Message object from the global pool.

peekData

Added in API level 1

fun peekData(): Bundle?

Like getData(), but does not lazily create the Bundle. A null is returned if the Bundle does not already exist. See getData for further information on this.

See Also

• #getData()
• #setData(Bundle)

recycle

Added in API level 1

fun recycle(): Unit

Return a Message instance to the global pool.

You MUST NOT touch the Message after calling this function because it has effectively been freed. It is an error to recycle a message that is currently enqueued or that is in the process of being delivered to a Handler.

sendToTarget

Added in API level 1

fun sendToTarget(): Unit

Sends this Message to the Handler specified by getTarget. Throws a null pointer exception if this field has not been set.

setAsynchronous

Added in API level 22

fun setAsynchronous(async: Boolean): Unit

Sets whether the message is asynchronous, meaning that it is not subject to Looper synchronization barriers.

Certain operations, such as view invalidation, may introduce synchronization barriers into the Looper's message queue to prevent subsequent messages from being delivered until some condition is met. In the case of view invalidation, messages which are posted after a call to android.view.View#invalidate are suspended by means of a synchronization barrier until the next frame is ready to be drawn. The synchronization barrier ensures that the invalidation request is completely handled before resuming.

Asynchronous messages are exempt from synchronization barriers. They typically represent interrupts, input events, and other signals that must be handled independently even while other work has been suspended.

Note that asynchronous messages may be delivered out of order with respect to synchronous messages although they are always delivered in order among themselves. If the relative order of these messages matters then they probably should not be asynchronous in the first place. Use with caution.

Parameters
async	Boolean: True if the message is asynchronous.

See Also

• #isAsynchronous()

setData

Added in API level 1

fun setData(data: Bundle!): Unit

Sets a Bundle of arbitrary data values. Use arg1 and arg2 members as a lower cost way to send a few simple integer values, if you can.

See Also

• #getData()
• #peekData()

setTarget

Added in API level 1

fun setTarget(target: Handler!): Unit

toString

Added in API level 1

fun toString(): String

Return
String	a string representation of the object.

writeToParcel

Added in API level 1

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 1

static val CREATOR: Parcelable.Creator<Message!>

arg1

Added in API level 1

var arg1: Int

arg1 and arg2 are lower-cost alternatives to using setData() if you only need to store a few integer values.

arg2

Added in API level 1

var arg2: Int

arg1 and arg2 are lower-cost alternatives to using setData() if you only need to store a few integer values.

obj

Added in API level 1

var obj: Any!

An arbitrary object to send to the recipient. When using Messenger to send the message across processes this can only be non-null if it contains a Parcelable of a framework class (not one implemented by the application). For other data transfer use setData.

Note that Parcelable objects here are not supported prior to the android.os.Build.VERSION_CODES#FROYO release.

replyTo

Added in API level 1

var replyTo: Messenger!

Optional Messenger where replies to this message can be sent. The semantics of exactly how this is used are up to the sender and receiver.

sendingUid

Added in API level 21

var sendingUid: Int

Optional field indicating the uid that sent the message. This is only valid for messages posted by a Messenger; otherwise, it will be -1.

what

Added in API level 1

var what: Int

User-defined message code so that the recipient can identify what this message is about. Each Handler has its own name-space for message codes, so you do not need to worry about yours conflicting with other handlers.