HandlerCompat
public
final
class
HandlerCompat
extends Object
java.lang.Object | |
↳ | androidx.core.os.HandlerCompat |
Helper for accessing features in Handler
.
Summary
Public methods | |
---|---|
static
Handler
|
createAsync(Looper looper, Handler.Callback callback)
Create a new Handler whose posted messages and runnables are not subject to synchronization barriers such as display vsync. |
static
Handler
|
createAsync(Looper looper)
Create a new Handler whose posted messages and runnables are not subject to synchronization barriers such as display vsync. |
static
boolean
|
hasCallbacks(Handler handler, Runnable r)
Checks if there are any pending posts of messages with callback |
static
boolean
|
postDelayed(Handler handler, Runnable r, Object token, long delayMillis)
Causes the Runnable r to be added to the message queue, to be run after the specified amount of time elapses. |
Inherited methods | |
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Public methods
createAsync
public static Handler createAsync (Looper looper, Handler.Callback callback)
Create a new Handler whose posted messages and runnables are not subject to synchronization barriers such as display vsync.
Messages sent to an async handler are guaranteed to be ordered with respect to one another, but not necessarily with respect to messages from other Handlers.
Parameters | |
---|---|
looper |
Looper : the Looper that the new Handler should be bound to |
callback |
Handler.Callback |
Returns | |
---|---|
Handler |
a new async Handler instance |
See also:
to create an async Handler without custom message handling. Compatibility behavior:
- SDK 28 and above, this method matches platform behavior.
- SDK 17 through 27, this method attempts to call the platform API via reflection, but may fail and return a synchronous handler instance.
- Below SDK 17, this method will always return a synchronous handler instance.
Handler.createAsync(Looper, Handler.Callback)
createAsync
public static Handler createAsync (Looper looper)
Create a new Handler whose posted messages and runnables are not subject to synchronization barriers such as display vsync.
Messages sent to an async handler are guaranteed to be ordered with respect to one another, but not necessarily with respect to messages from other Handlers.
Parameters | |
---|---|
looper |
Looper : the Looper that the new Handler should be bound to |
Returns | |
---|---|
Handler |
a new async Handler instance |
See also:
to create an async Handler with custom message handling. Compatibility behavior:
- SDK 28 and above, this method matches platform behavior.
- SDK 17 through 27, this method attempts to call the platform API via reflection, but may fail and return a synchronous handler instance.
- Below SDK 17, this method will always return a synchronous handler instance.
Handler.createAsync(Looper)
hasCallbacks
public static boolean hasCallbacks (Handler handler, Runnable r)
Checks if there are any pending posts of messages with callback r
in
the message queue.
Compatibility behavior:
- SDK 29 and above, this method matches platform behavior.
- SDK 16 through 28, this method attempts to call the platform API via reflection, but will throw an unchecked exception if the method has been altered from the AOSP implementation and cannot be called. This is unlikely, but there is no safe fallback case for this method and we must throw an exception as a result.
Parameters | |
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handler |
Handler : handler on which to call the method |
r |
Runnable : callback to look for in the message queue |
Returns | |
---|---|
boolean |
true if the callback is in the message queue |
See also:
postDelayed
public static boolean postDelayed (Handler handler, Runnable r, Object token, long delayMillis)
Causes the Runnable r to be added to the message queue, to be run
after the specified amount of time elapses.
The runnable will be run on the thread to which this handler
is attached.
The time-base is SystemClock.uptimeMillis()
.
Time spent in deep sleep will add an additional delay to execution.
Parameters | |
---|---|
handler |
Handler |
r |
Runnable : The Runnable that will be executed. |
token |
Object : An instance which can be used to cancel r via
Handler.removeCallbacksAndMessages(Object) . |
delayMillis |
long : The delay (in milliseconds) until the Runnable
will be executed. |
Returns | |
---|---|
boolean |
Returns true if the Runnable was successfully placed in to the message queue. Returns false on failure, usually because the looper processing the message queue is exiting. Note that a result of true does not mean the Runnable will be processed -- if the looper is quit before the delivery time of the message occurs then the message will be dropped. |