Handler

Handler

Handler()

Deprecated: Implicitly choosing a Looper during Handler construction can lead to bugs where operations are silently lost (if the Handler is not expecting new tasks and quits), crashes (if a handler is sometimes created on a thread without a Looper active), or race conditions, where the thread a handler is associated with is not what the author anticipated. Instead, use an java.util.concurrent.Executor or specify the Looper explicitly, using Looper.getMainLooper, android.view.View#getHandler, or similar. If the implicit thread local behavior is required for compatibility, use new Handler(Looper.myLooper()) to make it clear to readers.

Default constructor associates this handler with the Looper for the current thread. If this thread does not have a looper, this handler won't be able to receive messages so an exception is thrown.

Handler

Handler(callback: Handler.Callback?)

Deprecated: Implicitly choosing a Looper during Handler construction can lead to bugs where operations are silently lost (if the Handler is not expecting new tasks and quits), crashes (if a handler is sometimes created on a thread without a Looper active), or race conditions, where the thread a handler is associated with is not what the author anticipated. Instead, use an java.util.concurrent.Executor or specify the Looper explicitly, using Looper.getMainLooper, android.view.View#getHandler, or similar. If the implicit thread local behavior is required for compatibility, use new Handler(Looper.myLooper(), callback) to make it clear to readers.

Constructor associates this handler with the Looper for the current thread and takes a callback interface in which you can handle messages. If this thread does not have a looper, this handler won't be able to receive messages so an exception is thrown.

Handler

Handler(looper: Looper)

Use the provided Looper instead of the default one.

Handler

Handler(
    looper: Looper, 
    callback: Handler.Callback?)

Use the provided Looper instead of the default one and take a callback interface in which to handle messages.

createAsync

open static fun createAsync(looper: Looper): Handler

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.

createAsync

open static fun createAsync(
    looper: Looper, 
    callback: Handler.Callback
): Handler

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.

dispatchMessage

open fun dispatchMessage(msg: Message): Unit

Handle system messages here.

dump

fun dump(
    pw: Printer, 
    prefix: String
): Unit

getLooper

fun getLooper(): Looper

getMessageName

open fun getMessageName(message: Message): String

Returns a string representing the name of the specified message. The default implementation will either return the class name of the message callback if any, or the hexadecimal representation of the message "what" field.

handleMessage

open fun handleMessage(msg: Message): Unit

Subclasses must implement this to receive messages.

hasCallbacks

fun hasCallbacks(r: Runnable): Boolean

Check if there are any pending posts of messages with callback r in the message queue.

hasMessages

fun hasMessages(what: Int): Boolean

Check if there are any pending posts of messages with code 'what' in the message queue.

hasMessages

fun hasMessages(
    what: Int, 
    object: Any?
): Boolean

Check if there are any pending posts of messages with code 'what' and whose obj is 'object' in the message queue.

obtainMessage

fun obtainMessage(): Message

Returns a new Message from the global message pool. More efficient than creating and allocating new instances. The retrieved message has its handler set to this instance (Message.target == this). If you don't want that facility, just call Message.obtain() instead.

obtainMessage

fun obtainMessage(what: Int): Message

Same as obtainMessage(), except that it also sets the what member of the returned Message.

obtainMessage

fun obtainMessage(
    what: Int, 
    arg1: Int, 
    arg2: Int
): Message

Same as obtainMessage(), except that it also sets the what, arg1 and arg2 members of the returned Message.

obtainMessage

fun obtainMessage(
    what: Int, 
    arg1: Int, 
    arg2: Int, 
    obj: Any?
): Message

Same as obtainMessage(), except that it also sets the what, obj, arg1,and arg2 values on the returned Message.

obtainMessage

fun obtainMessage(
    what: Int, 
    obj: Any?
): Message

Same as obtainMessage(), except that it also sets the what and obj members of the returned Message.

post

fun post(r: Runnable): Boolean

Causes the Runnable r to be added to the message queue. The runnable will be run on the thread to which this handler is attached.

postAtFrontOfQueue

fun postAtFrontOfQueue(r: Runnable): Boolean

Posts a message to an object that implements Runnable. Causes the Runnable r to executed on the next iteration through the message queue. The runnable will be run on the thread to which this handler is attached. This method is only for use in very special circumstances -- it can easily starve the message queue, cause ordering problems, or have other unexpected side-effects.

postAtTime

fun postAtTime(
    r: Runnable, 
    token: Any?, 
    uptimeMillis: Long
): Boolean

Causes the Runnable r to be added to the message queue, to be run at a specific time given by uptimeMillis. The time-base is android.os.SystemClock#uptimeMillis. Time spent in deep sleep will add an additional delay to execution. The runnable will be run on the thread to which this handler is attached.

postAtTime

fun postAtTime(
    r: Runnable, 
    uptimeMillis: Long
): Boolean

Causes the Runnable r to be added to the message queue, to be run at a specific time given by uptimeMillis. The time-base is android.os.SystemClock#uptimeMillis. Time spent in deep sleep will add an additional delay to execution. The runnable will be run on the thread to which this handler is attached.

postDelayed

fun postDelayed(
    r: Runnable, 
    token: Any?, 
    delayMillis: Long
): Boolean

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 android.os.SystemClock#uptimeMillis. Time spent in deep sleep will add an additional delay to execution.

postDelayed

fun postDelayed(
    r: Runnable, 
    delayMillis: Long
): Boolean

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 android.os.SystemClock#uptimeMillis. Time spent in deep sleep will add an additional delay to execution.

removeCallbacks

fun removeCallbacks(r: Runnable): Unit

Remove any pending posts of Runnable r that are in the message queue.

removeCallbacks

fun removeCallbacks(
    r: Runnable, 
    token: Any?
): Unit

Remove any pending posts of Runnable r with Object token that are in the message queue. If token is null, all callbacks will be removed.

removeCallbacksAndMessages

fun removeCallbacksAndMessages(token: Any?): Unit

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.

removeMessages

fun removeMessages(what: Int): Unit

Remove any pending posts of messages with code 'what' that are in the message queue. Note that `Message#what` is 0 unless otherwise set. When calling `postMessage(Runnable)` or `postAtTime(Runnable, long)`, the `Runnable` is internally wrapped with a `Message` whose `what` is 0. Calling `removeMessages(0)` will remove all messages without a `what`, including posted `Runnable`s.

removeMessages

fun removeMessages(
    what: Int, 
    object: Any?
): Unit

Remove any pending posts of messages with code 'what' and whose obj is 'object' that are in the message queue. If object is null, all messages will be removed.

sendEmptyMessage

fun sendEmptyMessage(what: Int): Boolean

Sends a Message containing only the what value.

sendEmptyMessageAtTime

fun sendEmptyMessageAtTime(
    what: Int, 
    uptimeMillis: Long
): Boolean

Sends a Message containing only the what value, to be delivered at a specific time.

sendEmptyMessageDelayed

fun sendEmptyMessageDelayed(
    what: Int, 
    delayMillis: Long
): Boolean

Sends a Message containing only the what value, to be delivered after the specified amount of time elapses.

sendMessage

fun sendMessage(msg: Message): Boolean

Pushes a message onto the end of the message queue after all pending messages before the current time. It will be received in handleMessage, in the thread attached to this handler.

sendMessageAtFrontOfQueue

fun sendMessageAtFrontOfQueue(msg: Message): Boolean

Enqueue a message at the front of the message queue, to be processed on the next iteration of the message loop. You will receive it in handleMessage, in the thread attached to this handler. This method is only for use in very special circumstances -- it can easily starve the message queue, cause ordering problems, or have other unexpected side-effects.

sendMessageAtTime

open fun sendMessageAtTime(
    msg: Message, 
    uptimeMillis: Long
): Boolean

Enqueue a message into the message queue after all pending messages before the absolute time (in milliseconds) uptimeMillis. The time-base is android.os.SystemClock#uptimeMillis. Time spent in deep sleep will add an additional delay to execution. You will receive it in handleMessage, in the thread attached to this handler.

sendMessageDelayed

fun sendMessageDelayed(
    msg: Message, 
    delayMillis: Long
): Boolean

Enqueue a message into the message queue after all pending messages before (current time + delayMillis). You will receive it in handleMessage, in the thread attached to this handler.

toString

open fun toString(): String