/* * Copyright 2018 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package androidx.loader.app; import android.os.Bundle; import androidx.annotation.MainThread; import androidx.annotation.NonNull; import androidx.annotation.Nullable; import androidx.lifecycle.LifecycleOwner; import androidx.lifecycle.ViewModelStoreOwner; import androidx.loader.content.Loader; import java.io.FileDescriptor; import java.io.PrintWriter; /** * Static library support version of the framework's {@link 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 {@link androidx.fragment.app.FragmentActivity} to use this.
*/
public abstract class LoaderManager {
/**
* Callback interface for a client to interact with the manager.
*/
public interface LoaderCallbacks This will always be called from the process's main thread.
*
* @param id The ID whose loader is to be created.
* @param args Any arguments supplied by the caller.
* @return Return a new Loader instance that is ready to start loading.
*/
@MainThread
@NonNull
Loader This function is guaranteed to be called prior to the release of
* the last data that was supplied for this Loader. At this point
* you should remove all use of the old data (since it will be released
* soon), but should not do your own release of the data since its Loader
* owns it and will take care of that. The Loader will take care of
* management of its data so you don't have to. In particular:
*
* The Loader will monitor for changes to the data, and report
* them to you through new calls here. You should not monitor the
* data yourself. For example, if the data is a {@link android.database.Cursor}
* and you place it in a {@link android.widget.CursorAdapter}, use
* the {@link android.widget.CursorAdapter#CursorAdapter(android.content.Context,
* android.database.Cursor, int)} constructor without passing
* in either {@link android.widget.CursorAdapter#FLAG_AUTO_REQUERY}
* or {@link android.widget.CursorAdapter#FLAG_REGISTER_CONTENT_OBSERVER}
* (that is, use 0 for the flags argument). This prevents the CursorAdapter
* from doing its own observing of the Cursor, which is not needed since
* when a change happens you will get a new Cursor throw another call
* here.
* This will always be called from the process's main thread.
*
* @param loader The Loader that has finished.
* @param data The data generated by the Loader.
*/
@MainThread
void onLoadFinished(@NonNull Loader This will always be called from the process's main thread.
*
* @param loader The Loader that is being reset.
*/
@MainThread
void onLoaderReset(@NonNull Loader 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 {@link 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.
*
* @param id A unique identifier for this loader. Can be whatever you want.
* Identifiers are scoped to a particular LoaderManager instance.
* @param 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.
* @param callback Interface the LoaderManager will call to report about
* changes in the state of the loader. Required.
*/
@MainThread
@NonNull
public abstract Must be called from the process's main thread.
*
* @param id A unique identifier for this loader. Can be whatever you want.
* Identifiers are scoped to a particular LoaderManager instance.
* @param args Optional arguments to supply to the loader at construction.
* @param callback Interface the LoaderManager will call to report about
* changes in the state of the loader. Required.
*/
@MainThread
@NonNull
public abstract Must be called from the process's main thread.
*/
@MainThread
public abstract void destroyLoader(int id);
/**
* Return the Loader with the given id or null if no matching Loader
* is found.
*/
@Nullable
public abstract
* Call this only if you are implementing a {@link LifecycleOwner} where the views/elements that
* developers are likely to use in {@link LoaderCallbacks#onLoadFinished(Loader, Object)} can be
* created and destroyed multiple times without the {@link LifecycleOwner} itself being
* destroyed. Call this when the views/elements are being destroyed to ensure that the data
* is redelivered upon recreation.
*/
public abstract void markForRedelivery();
/**
* Print the LoaderManager's state into the given stream.
*
* @param prefix Text to print at the front of each line.
* @param fd The raw file descriptor that the dump is being sent to.
* @param writer A PrintWriter to which the dump is to be set.
* @param args Additional arguments to the dump request.
* @deprecated Use {@link #enableDebugLogging(boolean)} to understand the series of operations
* performed by LoaderManager.
*/
@Deprecated
public abstract void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args);
/**
* 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.
*/
public static void enableDebugLogging(boolean enabled) {
LoaderManagerImpl.DEBUG = enabled;
}
/**
* Returns true if any loaders managed are currently running and have not
* returned data to the application yet.
*/
public boolean hasRunningLoaders() { return false; }
}
*
*
*