Message

CREATOR

public static final Creator<Message> CREATOR

arg1

public int arg1

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

arg2

public int arg2

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

obj

public Object obj

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(Bundle).

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

replyTo

public Messenger replyTo

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

public int sendingUid

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

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. If not specified, this value is 0. Use values other than 0 to indicate custom message codes.

Message

public Message ()

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

copyFrom

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.

describeContents

public int describeContents ()

Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. For example, if the object will include a file descriptor in the output of writeToParcel(android.os.Parcel, int), the return value of this method must include the CONTENTS_FILE_DESCRIPTOR bit.

getCallback

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 Handler.handleMessage(Message).

getData

public Bundle getData ()

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.

getTarget

public Handler getTarget ()

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

public long getWhen ()

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

isAsynchronous

public boolean isAsynchronous ()

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

obtain

public static Message obtain (Handler h)

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

obtain

public static Message obtain (Handler h, 
                int what)

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

obtain

public static Message obtain (Handler h, 
                Runnable callback)

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

obtain

public static Message obtain (Message orig)

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

obtain

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.

obtain

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.

obtain

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

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

obtain

public static Message obtain ()

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

peekData

public Bundle peekData ()

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.

recycle

public void recycle ()

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

public void sendToTarget ()

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

setAsynchronous

public void setAsynchronous (boolean async)

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 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.

setData

public void setData (Bundle data)

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.

setTarget

public void setTarget (Handler target)

toString

public String toString ()

Returns a string representation of the object.

writeToParcel

public void writeToParcel (Parcel dest, 
                int flags)

Flatten this object in to a Parcel.