AsyncTaskLoader

Kotlin |Java

abstract class AsyncTaskLoader<D : Any!> : Loader<D>

kotlin.Any
↳	androidx.loader.content.Loader<D>
	↳	androidx.loader.content.AsyncTaskLoader

Known Direct Subclasses

CursorLoader

Static library support version of the framework's android.content.CursorLoader.

Static library support version of the framework's android.content.AsyncTaskLoader. Used to write apps that run on platforms prior to Android 3.0. When running on Android 3.0 or above, this implementation is still used; it does not try to switch to the framework's implementation. See the framework SDK documentation for a class overview.

Summary

Public constructors
`<init>(@NonNull context: Context)`

Public methods
open Unit	`cancelLoadInBackground()` Called on the main thread to abort a load in progress.
open Unit	`dump(prefix: String!, fd: FileDescriptor!, writer: PrintWriter!, args: Array<String!>!)`
open Boolean	`isLoadInBackgroundCanceled()` Returns true if the current invocation of `loadInBackground` is being canceled.
abstract D?	`loadInBackground()` Called on a worker thread to perform the actual load and to return the result of the load operation.
open Unit	`onCanceled(@Nullable data: D?)` Called if the task was canceled before it was completed.
open Unit	`setUpdateThrottle(delayMS: Long)` Set amount to throttle updates by.

Protected methods
open Executor	`getExecutor()` Returns the `Executor` to use for this `Loader`'s `AsyncTask`s.
open Boolean	`onCancelLoad()`
open Unit	`onForceLoad()`
open D?	`onLoadInBackground()` Calls `loadInBackground()`.

Inherited functions

From class Loader

`Unit`	`abandon()` This function will normally be called for you automatically by `LoaderManager` when restarting a Loader. When using a Loader with `LoaderManager`, you must not call this method yourself, or you will conflict with its management of the Loader. Tell the Loader that it is being abandoned. This is called prior to `reset` to have it retain its current data but not report any new data. Must be called from the process's main thread.
`Boolean`	`cancelLoad()` Attempt to cancel the current load task. Must be called on the main thread of the process. Cancellation is not an immediate operation, since the load is performed in a background thread. If there is currently a load in progress, this method requests that the load be canceled, and notes this is the case; once the background thread has completed its work its remaining state will be cleared. If another load request comes in during this time, it will be held until the canceled load is complete.
`Unit`	`commitContentChanged()` Commit that you have actually fully processed a content change that was returned by `takeContentChanged`. This is for use with `rollbackContentChanged()` to handle situations where a load is cancelled. Call this when you have completely processed a load without it being cancelled.
`String`	`dataToString(@Nullable data: D?)` For debugging, converts an instance of the Loader's data class to a string that can be printed. Must handle a null data.
`Unit`	`deliverCancellation()` Informs the registered `OnLoadCanceledListener` that the load has been canceled. Should only be called by subclasses. Must be called from the process's main thread.
`Unit`	`deliverResult(@Nullable data: D?)` Sends the result of the load to the registered listener. Should only be called by subclasses. Must be called from the process's main thread.
`Unit`	`forceLoad()` Force an asynchronous load. Unlike `startLoading()` this will ignore a previously loaded data set and load a new one. This simply calls through to the implementation's `onForceLoad()`. You generally should only call this when the loader is started -- that is, `isStarted()` returns true. Must be called from the process's main thread.
`Context`	`getContext()`
`Int`	`getId()`
`Boolean`	`isAbandoned()` Return whether this loader has been abandoned. In this state, the loader must not report any new data, and must keep its last reported data valid until it is finally reset.
`Boolean`	`isReset()` Return whether this load has been reset. That is, either the loader has not yet been started for the first time, or its `reset()` has been called.
`Boolean`	`isStarted()` Return whether this load has been started. That is, its `startLoading()` has been called and no calls to `stopLoading()` or `reset()` have yet been made.
`Unit`	`onAbandon()` Subclasses implement this to take care of being abandoned. This is an optional intermediate state prior to `onReset()` -- it means that the client is no longer interested in any new data from the loader, so the loader must not report any further updates. However, the loader must keep its last reported data valid until the final `onReset()` happens. You can retrieve the current abandoned state with `isAbandoned`. This will always be called from the process's main thread.
`Unit`	`onContentChanged()` Called when `ForceLoadContentObserver` detects a change. The default implementation checks to see if the loader is currently started; if so, it simply calls `forceLoad()`; otherwise, it sets a flag so that `takeContentChanged()` returns true. Must be called from the process's main thread.
`Unit`	`onReset()` Subclasses must implement this to take care of resetting their loader, as per `reset()`. This is not called by clients directly, but as a result of a call to `reset()`. This will always be called from the process's main thread.
`Unit`	`onStartLoading()` Subclasses must implement this to take care of loading their data, as per `startLoading()`. This is not called by clients directly, but as a result of a call to `startLoading()`. This will always be called from the process's main thread.
`Unit`	`onStopLoading()` Subclasses must implement this to take care of stopping their loader, as per `stopLoading()`. This is not called by clients directly, but as a result of a call to `stopLoading()`. This will always be called from the process's main thread.
`Unit`	`registerListener(id: Int, @NonNull listener: Loader.OnLoadCompleteListener<D>)` Registers a class that will receive callbacks when a load is complete. The callback will be called on the process's main thread so it's safe to pass the results to widgets. Must be called from the process's main thread.
`Unit`	`registerOnLoadCanceledListener(@NonNull listener: Loader.OnLoadCanceledListener<D>)` Registers a listener that will receive callbacks when a load is canceled. The callback will be called on the process's main thread so it's safe to pass the results to widgets. Must be called from the process's main thread.
`Unit`	`reset()` This function will normally be called for you automatically by `LoaderManager` when destroying a Loader. When using a Loader with `LoaderManager`, you must not call this method yourself, or you will conflict with its management of the Loader. Resets the state of the Loader. The Loader should at this point free all of its resources, since it may never be called again; however, its `startLoading()` may later be called at which point it must be able to start running again. This updates the Loader's internal state so that `isStarted()` and `isReset()` will return the correct values, and then calls the implementation's `onReset()`. Must be called from the process's main thread.
`Unit`	`rollbackContentChanged()` Report that you have abandoned the processing of a content change that was returned by `takeContentChanged()` and would like to rollback to the state where there is again a pending content change. This is to handle the case where a data load due to a content change has been canceled before its data was delivered back to the loader.
`Unit`	`startLoading()` This function will normally be called for you automatically by `LoaderManager` when the associated fragment/activity is being started. When using a Loader with `LoaderManager`, you must not call this method yourself, or you will conflict with its management of the Loader. Starts an asynchronous load of the Loader's data. When the result is ready the callbacks will be called on the process's main thread. If a previous load has been completed and is still valid the result may be passed to the callbacks immediately. The loader will monitor the source of the data set and may deliver future callbacks if the source changes. Calling `stopLoading` will stop the delivery of callbacks. This updates the Loader's internal state so that `isStarted()` and `isReset()` will return the correct values, and then calls the implementation's `onStartLoading()`. Must be called from the process's main thread.
`Unit`	`stopLoading()` This function will normally be called for you automatically by `LoaderManager` when the associated fragment/activity is being stopped. When using a Loader with `LoaderManager`, you must not call this method yourself, or you will conflict with its management of the Loader. Stops delivery of updates until the next time `startLoading()` is called. Implementations should not invalidate their data at this point -- clients are still free to use the last data the loader reported. They will, however, typically stop reporting new data if the data changes; they can still monitor for changes, but must not report them to the client until and if `startLoading()` is later called. This updates the Loader's internal state so that `isStarted()` will return the correct value, and then calls the implementation's `onStopLoading()`. Must be called from the process's main thread.
`Boolean`	`takeContentChanged()` Take the current flag indicating whether the loader's content had changed while it was stopped. If it had, true is returned and the flag is cleared.
`String`	`toString()`
`Unit`	`unregisterListener(@NonNull listener: Loader.OnLoadCompleteListener<D>)` Remove a listener that was previously added with `registerListener`. Must be called from the process's main thread.
`Unit`	`unregisterOnLoadCanceledListener(@NonNull listener: Loader.OnLoadCanceledListener<D>)` Unregisters a listener that was previously added with `registerOnLoadCanceledListener`. Must be called from the process's main thread.

Public constructors

<init>

AsyncTaskLoader(@NonNull context: Context)

Public methods

cancelLoadInBackground

open fun cancelLoadInBackground(): Unit

Called on the main thread to abort a load in progress. Override this method to abort the current invocation of loadInBackground that is running in the background on a worker thread. This method should do nothing if loadInBackground has not started running or if it has already finished.

See Also

#loadInBackground

dump

open fun dump(prefix: String!, fd: FileDescriptor!, writer: PrintWriter!, args: Array<String!>!): Unit

Deprecated: Consider using LoaderManager#enableDebugLogging(boolean) to understand the series of operations performed by LoaderManager.

Parameters
`prefix`	String!: Text to print at the front of each line.
`fd`	String!: The raw file descriptor that the dump is being sent to.
`writer`	String!: A PrintWriter to which the dump is to be set.
`args`	String!: Additional arguments to the dump request.

isLoadInBackgroundCanceled

open fun isLoadInBackgroundCanceled(): Boolean

Returns true if the current invocation of loadInBackground is being canceled.

Return
Boolean: True if the current invocation of `loadInBackground` is being canceled.

See Also

#loadInBackground

loadInBackground

@Nullable abstract fun loadInBackground(): D?

Called on a worker thread to perform the actual load and to return the result of the load operation. Implementations should not deliver the result directly, but should return them from this method, which will eventually end up calling deliverResult on the UI thread. If implementations need to process the results on the UI thread they may override deliverResult and do so there. To support cancellation, this method should periodically check the value of isLoadInBackgroundCanceled and terminate when it returns true. Subclasses may also override cancelLoadInBackground to interrupt the load directly instead of polling isLoadInBackgroundCanceled. When the load is canceled, this method may either return normally or throw OperationCanceledException. In either case, the Loader will call onCanceled to perform post-cancellation cleanup and to dispose of the result object, if any.

Return
D?: The result of the load operation.

Exceptions
`OperationCanceledException`	if the load is canceled during execution.

See Also

#isLoadInBackgroundCanceled#cancelLoadInBackground#onCanceled

onCanceled

open fun onCanceled(@Nullable data: D?): Unit

Called if the task was canceled before it was completed. Gives the class a chance to clean up post-cancellation and to properly dispose of the result.

Parameters
`data`	D?: The value that was returned by `loadInBackground`, or null if the task threw `OperationCanceledException`.

setUpdateThrottle

open fun setUpdateThrottle(delayMS: Long): Unit

Set amount to throttle updates by. This is the minimum time from when the last loadInBackground() call has completed until a new load is scheduled.

Parameters
`delayMS`	Long: Amount of delay, in milliseconds.

Protected methods

getExecutor

@NonNull protected open fun getExecutor(): Executor

Returns the Executor to use for this Loader's AsyncTasks. By default AsyncTask#THREAD_POOL_EXECUTOR will be used. Override this method to return a custom executor. Note that this method will only be called once before this Loader's first AsyncTask is run. It is up to the Loader to shut down the Executor at the appropriate place (e.g. in onAbandon()) if necessary.

Return
Executor: the `Executor` to use for this `Loader`'s `AsyncTask`s.

onCancelLoad

protected open fun onCancelLoad(): Boolean

onForceLoad

protected open fun onForceLoad(): Unit

onLoadInBackground

@Nullable protected open fun onLoadInBackground(): D?

Calls loadInBackground(). This method is reserved for use by the loader framework. Subclasses should override loadInBackground instead of this method.

Return
D?: The result of the load operation.

Exceptions
`OperationCanceledException`	if the load is canceled during execution.

See Also

#loadInBackground