android.os
public final class
public final class
android.os.Message
| java.lang.Object | ||
| android.os.Message | Parcelable | |
Defines a Message that can be placed in a MessageQueue for scheduled execution of a Runnable object. The Message must be given a Handler that is in charge scheduling the Message and managing its results.
While the constructor of Message is public, the best way to get one of these is to call Message.obtain() or to first create the Handler object that will manage the Message and call one of the Handler.obtainMessage() methods, which will pull a Message from a pool of recycled objects.
Summary
Constants
| Value | ||||
|---|---|---|---|---|
| Creator | 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 | Runnable | callback | A callback object to receive the message. | ||
| public | Object | obj | An arbitrary object to send to the recipient. | ||
| public | Handler | target | A Handler implementation that will receive this message. | ||
| public | int | what | User-defined message code so that the recipient can identify what this message is about. | ||
| public | long | when | The targeted delivery time of this message,in milliseconds from now. |
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. | |||||
| HashMap | getData() | ||||
| Obtains a HashMap of arbitrary data associated with this event, lazily creating it if necessary. | |||||
| static | Message | obtain() | |||
| Return a new Message instance from the global pool. | |||||
| 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, 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. | |||||
| HashMap | peekData() | ||||
| Like getData(), but does not lazily create the HashMap. | |||||
| void | recycle() | ||||
| Return a Message instance to the global pool. | |||||
| void | sendToTarget() | ||||
| Sends this Message to the Handler specified by target. | |||||
| void | setData(HashMap data) | ||||
| Sets a HashMap of arbitrary data values. | |||||
| String | toString() | ||||
| Answers a string containing a concise, human-readable description of the receiver. | |||||
| void | writeToParcel(Parcel dest) | ||||
| Writes all of the Message's data to a given Parcel object, including any HashMap data. | |||||
Methods inherited
from class
java.lang.Object
Methods inherited
from interface
android.os.Parcelable
Details
Constants
public static final Creator 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 Runnable callback
A callback object to receive the message. 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 Object obj
An arbitrary object to send to the recipient.
public Handler target
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 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 long when
The targeted delivery time of this message,in milliseconds from now.
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 HashMap data.
Parameters
| o | The Message to copy over to this one. |
|---|
public HashMap getData()
Obtains a HashMap of arbitrary data associated with this
event, lazily creating it if necessary. Set this value by calling
setData(HashMap).
public static Message obtain()
Return a new Message instance from the global pool. Allows us to
avoid allocating new Java objects in many cases.
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, 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 HashMap peekData()
Like getData(), but does not lazily create the HashMap. A null
is returned if the HashMap does not already exist. Set this value by
calling setData(HashMap).
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 target. Throws a null pointer
exception if this field has not been set.
public void setData(HashMap data)
Sets a HashMap of arbitrary data values. Use arg1 and
arg1 members
as a lower cost way to send a few simple integer values, if you can.
Retrieve the data with getData() or peekData().
public String toString()
Answers a string containing a concise, human-readable description of the
receiver.