android.support.v4.app
Class LoaderManager

java.lang.Object
  android.support.v4.app.LoaderManager

public abstract class LoaderManager
extends Object

Static library support version of the framework's 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 FragmentActivity to use this.

Nested Class Summary

static interface

LoaderManager.LoaderCallbacks<D> Callback interface for a client to interact with the manager.

Constructor Summary

LoaderManager()

Method Summary

abstract void	destroyLoader(int id) Stops and removes the loader with the given ID.
abstract void	dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) Print the LoaderManager's state into the given stream.
static void	enableDebugLogging(boolean enabled) Control whether the framework's internal loader manager debugging logs are turned on.
abstract <D> Loader<D>	getLoader(int id) Return the Loader with the given id or null if no matching Loader is found.
boolean	hasRunningLoaders() Returns true if any loaders managed are currently running and have not returned data to the application yet.
abstract <D> Loader<D>	initLoader(int id, android.os.Bundle args, LoaderManager.LoaderCallbacks<D> callback) Ensures a loader is initialized and active.
abstract <D> Loader<D>	restartLoader(int id, android.os.Bundle args, LoaderManager.LoaderCallbacks<D> callback) Starts a new or restarts an existing Loader in this manager, registers the callbacks to it, and (if the activity/fragment is currently started) starts loading it.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LoaderManager

public LoaderManager()

Method Detail

initLoader

public abstract <D> Loader<D> initLoader(int id,
                                         android.os.Bundle args,
                                         LoaderManager.LoaderCallbacks<D> callback)

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 LoaderManager.LoaderCallbacks.onLoadFinished(android.support.v4.content.Loader, D) will be called immediately (inside of this function), so you must be prepared for this to happen.

Parameters:

id - A unique identifier for this loader. Can be whatever you want. Identifiers are scoped to a particular LoaderManager instance.

args - 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 - Interface the LoaderManager will call to report about changes in the state of the loader. Required.

restartLoader

public abstract <D> Loader<D> restartLoader(int id,
                                            android.os.Bundle args,
                                            LoaderManager.LoaderCallbacks<D> callback)

Starts a new or restarts an existing 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.

Parameters:

id - A unique identifier for this loader. Can be whatever you want. Identifiers are scoped to a particular LoaderManager instance.

args - Optional arguments to supply to the loader at construction.

callback - Interface the LoaderManager will call to report about changes in the state of the loader. Required.

destroyLoader

public abstract void destroyLoader(int id)

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

getLoader

public abstract <D> Loader<D> getLoader(int id)

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

dump

public abstract void dump(String prefix,
                          FileDescriptor fd,
                          PrintWriter writer,
                          String[] args)

Print the LoaderManager's state into the given stream.

Parameters:

prefix - Text to print at the front of each line.

fd - The raw file descriptor that the dump is being sent to.

writer - A PrintWriter to which the dump is to be set.

args - Additional arguments to the dump request.

enableDebugLogging

public static void enableDebugLogging(boolean enabled)

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.

hasRunningLoaders

public boolean hasRunningLoaders()

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