LoaderManager

Kotlin |Java

abstract class LoaderManager

kotlin.Any
↳	androidx.loader.app.LoaderManager

Static library support version of the framework's android.app.LoaderManager. 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.

Your activity must derive from androidx.fragment.app.FragmentActivity to use this.

Summary

Nested classes
abstract	LoaderCallbacks Callback interface for a client to interact with the manager.

Public constructors
<init>() Static library support version of the framework's android.app.LoaderManager.

Public methods
abstract Unit	destroyLoader(id: Int) Stops and removes the loader with the given ID.
abstract Unit	dump(prefix: String!, fd: FileDescriptor!, writer: PrintWriter!, args: Array<String!>!) Print the LoaderManager's state into the given stream.
open static Unit	enableDebugLogging(enabled: Boolean) Control whether the framework's internal loader manager debugging logs are turned on.
open static LoaderManager	getInstance(@NonNull owner: T) Gets a LoaderManager associated with the given owner, such as a androidx.fragment.app.FragmentActivity or androidx.fragment.app.Fragment.
abstract Loader<D>?	getLoader(id: Int) Return the Loader with the given id or null if no matching Loader is found.
open Boolean	hasRunningLoaders() Returns true if any loaders managed are currently running and have not returned data to the application yet.
abstract Loader<D>	initLoader(id: Int, @Nullable args: Bundle?, @NonNull callback: LoaderManager.LoaderCallbacks<D>) Ensures a loader is initialized and active.
abstract Unit	markForRedelivery() Mark all Loaders associated with this LoaderManager for redelivery of their current data (if any), waiting for the next time the Loader is started if it is currently stopped.
abstract Loader<D>	restartLoader(id: Int, @Nullable args: Bundle?, @NonNull callback: LoaderManager.LoaderCallbacks<D>) Starts a new or restarts an existing android.content.Loader in this manager, registers the callbacks to it, and (if the activity/fragment is currently started) starts loading it.

Public constructors

<init>

LoaderManager()

Static library support version of the framework's android.app.LoaderManager. 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.

Your activity must derive from androidx.fragment.app.FragmentActivity to use this.

Public methods

destroyLoader

@MainThread abstract fun destroyLoader(id: Int): Unit

Stops and removes the loader with the given ID. If this loader had previously reported data to the client through LoaderCallbacks#onLoadFinished(Loader, Object), a call will be made to LoaderCallbacks#onLoaderReset(Loader).

Must be called from the process's main thread.

dump

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

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

Print the LoaderManager's state into the given stream.

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

enableDebugLogging

open static fun enableDebugLogging(enabled: Boolean): Unit

Control whether the framework's internal loader manager debugging logs are turned on. If enabled, you will see output in logcat as the framework performs loader operations.

getInstance

@NonNull open static fun <T> getInstance(@NonNull owner: T): LoaderManager where T : LifecycleOwner!, T : ViewModelStoreOwner!

Gets a LoaderManager associated with the given owner, such as a androidx.fragment.app.FragmentActivity or androidx.fragment.app.Fragment.

Parameters
owner	T: The owner that should be used to create the returned LoaderManager
<T>	A class that maintains its own android.arch.lifecycle.Lifecycle and android.arch.lifecycle.ViewModelStore. For instance, androidx.fragment.app.FragmentActivity or androidx.fragment.app.Fragment.

Return
LoaderManager	A valid LoaderManager

getLoader

@Nullable abstract fun <D : Any!> getLoader(id: Int): Loader<D>?

Return the Loader with the given id or null if no matching Loader is found.

hasRunningLoaders

open fun hasRunningLoaders(): Boolean

Returns true if any loaders managed are currently running and have not returned data to the application yet.

initLoader

@MainThread @NonNull abstract fun <D : Any!> initLoader(
    id: Int, 
    @Nullable args: Bundle?, 
    @NonNull callback: LoaderManager.LoaderCallbacks<D>
): Loader<D>

Ensures a loader is initialized and active. If the loader doesn't already exist, one is created and (if the activity/fragment is currently started) starts the loader. Otherwise the last created loader is re-used.

In either case, the given callback is associated with the loader, and will be called as the loader state changes. If at the point of call the caller is in its started state, and the requested loader already exists and has generated its data, then callback LoaderCallbacks#onLoadFinished will be called immediately (inside of this function), so you must be prepared for this to happen.

Must be called from the process's main thread.

Parameters
id	Int: A unique identifier for this loader. Can be whatever you want. Identifiers are scoped to a particular LoaderManager instance.
args	Bundle?: Optional arguments to supply to the loader at construction. If a loader already exists (a new one does not need to be created), this parameter will be ignored and the last arguments continue to be used.
callback	LoaderManager.LoaderCallbacks<D>: Interface the LoaderManager will call to report about changes in the state of the loader. Required.

markForRedelivery

abstract fun markForRedelivery(): Unit

Mark all Loaders associated with this LoaderManager for redelivery of their current data (if any), waiting for the next time the Loader is started if it is currently stopped. In cases where no data has yet been delivered, this is effectively a no-op. In cases where data has already been delivered via LoaderCallbacks#onLoadFinished(Loader, Object), this will ensure that LoaderCallbacks#onLoadFinished(Loader, Object) is called again with the same data.

Call this only if you are implementing a LifecycleOwner where the views/elements that developers are likely to use in LoaderCallbacks#onLoadFinished(Loader, Object) can be created and destroyed multiple times without the LifecycleOwner itself being destroyed. Call this when the views/elements are being destroyed to ensure that the data is redelivered upon recreation.

restartLoader

@MainThread @NonNull abstract fun <D : Any!> restartLoader(
    id: Int, 
    @Nullable args: Bundle?, 
    @NonNull callback: LoaderManager.LoaderCallbacks<D>
): Loader<D>

Starts a new or restarts an existing android.content.Loader in this manager, registers the callbacks to it, and (if the activity/fragment is currently started) starts loading it. If a loader with the same id has previously been started it will automatically be destroyed when the new loader completes its work. The callback will be delivered before the old loader is destroyed.

Must be called from the process's main thread.

Parameters
id	Int: A unique identifier for this loader. Can be whatever you want. Identifiers are scoped to a particular LoaderManager instance.
args	Bundle?: Optional arguments to supply to the loader at construction.
callback	LoaderManager.LoaderCallbacks<D>: Interface the LoaderManager will call to report about changes in the state of the loader. Required.