public final class

Message

extends Object
implements Parcelable
java.lang.Object
   ↳ android.os.Message

Class Overview

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 Message.obtain() or one of the Handler.obtainMessage() methods, which will pull them from a pool of recycled objects.

Summary

Constants
Creator<Message> CREATOR
[Expand]
Inherited Constants
From interface android.os.Parcelable
Fields
public int arg1 arg1 and arg2 are lower-cost alternatives to using setData() if you only need to store a few integer values.
public int arg2 arg1 and arg2 are lower-cost alternatives to using setData() if you only need to store a few integer values.
public Object obj An arbitrary object to send to the recipient.
public Messenger replyTo Optional Messenger where replies to this message can be sent.
public int what User-defined message code so that the recipient can identify what this message is about.
Public Constructors
Message()
Constructor (but the preferred way to get a Message is to call Message.obtain()).
Public Methods
void copyFrom(Message o)
Make this message like o.
int describeContents()
Describe the kinds of special objects contained in this Parcelable's marshalled representation.
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 a Handler implementation that will receive this message.
long getWhen()
Return the targeted delivery time of this message, in milliseconds.
static Message obtain()
Return a new Message instance from the global pool.
static Message obtain(Message orig)
Same as obtain(), but copies the values of an existing message (including its target) into the new one.
static Message obtain(Handler h)
Same as obtain(), but sets the value for the target member on the Message returned.
static Message obtain(Handler h, Runnable callback)
Same as obtain(Handler), but assigns a callback Runnable on the Message that is returned.
static Message obtain(Handler h, int what, int arg1, int arg2)
Same as obtain(), but sets the values of the target, what, arg1, and arg2 members.
static Message obtain(Handler h, int what)
Same as obtain(), but sets the values for both target and what members on the Message.
static Message obtain(Handler h, int what, Object obj)
Same as obtain(), but sets the values of the target, what, and obj members.
static Message obtain(Handler h, int what, int arg1, int arg2, Object obj)
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.
void recycle()
Return a Message instance to the global pool.
void sendToTarget()
Sends this Message to the Handler specified by getTarget().
void setData(Bundle data)
Sets a Bundle of arbitrary data values.
void setTarget(Handler target)
String toString()
Returns a string containing a concise, human-readable description of this object.
void writeToParcel(Parcel dest, int flags)
Flatten this object in to a Parcel.
[Expand]
Inherited Methods
From class java.lang.Object
From interface android.os.Parcelable

Constants

public static final Creator<Message> CREATOR

Fields

public int arg1

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

public int arg2

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

public Object obj

An arbitrary object to send to the recipient. This must be null when sending messages across processes.

public Messenger replyTo

Optional Messenger where replies to this message can be sent.

public int what

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.

Public Constructors

public Message ()

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

Public Methods

public void copyFrom (Message o)

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.

public int describeContents ()

Describe the kinds of special objects contained in this Parcelable's marshalled representation.

Returns
  • a bitmask indicating the set of special object types marshalled by the Parcelable.

public Runnable getCallback ()

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 handleMessage(Message).

public Bundle getData ()

Obtains a Bundle of arbitrary data associated with this event, lazily creating it if necessary. Set this value by calling setData(Bundle).

public Handler getTarget ()

Retrieve the a 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.

public long getWhen ()

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

public static Message obtain ()

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

public static Message obtain (Message orig)

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

Parameters
orig Original message to copy.
Returns
  • A Message object from the global pool.

public static Message obtain (Handler h)

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

Parameters
h Handler to assign to the returned Message object's target member.
Returns
  • A Message object from the global pool.

public static Message obtain (Handler h, Runnable callback)

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

Parameters
h Handler to assign to the returned Message object's target member.
callback Runnable that will execute when the message is handled.
Returns
  • A Message object from the global pool.

public static Message obtain (Handler h, int what, int arg1, int arg2)

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

Parameters
h The target value to set.
what The what value to set.
arg1 The arg1 value to set.
arg2 The arg2 value to set.
Returns
  • A Message object from the global pool.

public static Message obtain (Handler h, int what)

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

Parameters
h Value to assign to the target member.
what Value to assign to the what member.
Returns
  • A Message object from the global pool.

public static Message obtain (Handler h, int what, Object obj)

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

Parameters
h The target value to set.
what The what value to set.
obj The object method to set.
Returns
  • A Message object from the global pool.

public static Message obtain (Handler h, int what, int arg1, int arg2, Object obj)

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

Parameters
h The target value to set.
what The what value to set.
arg1 The arg1 value to set.
arg2 The arg2 value to set.
obj The obj value to set.
Returns
  • A Message object from the global pool.

public Bundle peekData ()

Like getData(), but does not lazily create the Bundle. A null is returned if the Bundle does not already exist.

public void recycle ()

Return a Message instance to the global pool. You MUST NOT touch the Message after calling this function -- it has effectively been freed.

public void sendToTarget ()

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

public void setData (Bundle data)

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

public void setTarget (Handler target)

public String toString ()

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 simply concatenates the class name, the '@' sign and a hexadecimal representation of the object's hashCode(), that is, it is equivalent to the following expression: 

 getClass().getName() + '@' + Integer.toHexString(hashCode())

Returns
  • a printable representation of this object.

public void writeToParcel (Parcel dest, int flags)

Flatten this object in to a Parcel.

Parameters
dest The Parcel in which the object should be written.
flags Additional flags about how the object should be written. May be 0 or PARCELABLE_WRITE_RETURN_VALUE.