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/*
* Copyright (C) 2010 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 android.app;
import android.content.Loader;
import android.content.Loader.OnLoadCompleteListener;
import android.os.Bundle;
import android.util.SparseArray;
/**
* Object associated with an {@link Activity} or {@link Fragment} for managing
* one or more {@link android.content.Loader} instances associated with it.
*/
public class LoaderManager {
/**
* Callback interface for a client to interact with the manager.
*/
public interface LoaderCallbacks<D> {
public Loader<D> onCreateLoader(int id, Bundle args);
public void onLoadFinished(Loader<D> loader, D data);
}
final class LoaderInfo implements Loader.OnLoadCompleteListener<Object> {
public Bundle args;
public Loader<Object> loader;
public LoaderManager.LoaderCallbacks<Object> callback;
@Override public void onLoadComplete(Loader<Object> loader, Object data) {
// Notify of the new data so the app can switch out the old data before
// we try to destroy it.
callback.onLoadFinished(loader, data);
// Look for an inactive loader and destroy it if found
int id = loader.getId();
LoaderInfo info = mInactiveLoaders.get(id);
if (info != null) {
Loader<Object> oldLoader = info.loader;
if (oldLoader != null) {
oldLoader.destroy();
}
mInactiveLoaders.remove(id);
}
}
}
SparseArray<LoaderInfo> mLoaders = new SparseArray<LoaderInfo>();
SparseArray<LoaderInfo> mInactiveLoaders = new SparseArray<LoaderInfo>();
boolean mStarted;
LoaderManager(boolean started) {
mStarted = started;
}
/**
* Associates a loader with this managers, registers the callbacks on it,
* and starts it loading. 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.
*/
@SuppressWarnings("unchecked")
public <D> Loader<D> startLoading(int id, Bundle args, LoaderManager.LoaderCallbacks<D> callback) {
LoaderInfo info = mLoaders.get(id);
if (info != null) {
// Keep track of the previous instance of this loader so we can destroy
// it when the new one completes.
mInactiveLoaders.put(id, info);
}
info = new LoaderInfo();
info.args = args;
info.callback = (LoaderManager.LoaderCallbacks<Object>)callback;
mLoaders.put(id, info);
Loader<D> loader = callback.onCreateLoader(id, args);
info.loader = (Loader<Object>)loader;
if (mStarted) {
// The activity will start all existing loaders in it's onStart(), so only start them
// here if we're past that point of the activitiy's life cycle
loader.registerListener(id, (OnLoadCompleteListener<D>)info);
loader.startLoading();
}
return loader;
}
/**
* Stops and removes the loader with the given ID.
*/
public void stopLoading(int id) {
if (mLoaders != null) {
int idx = mLoaders.indexOfKey(id);
if (idx >= 0) {
LoaderInfo info = mLoaders.valueAt(idx);
mLoaders.removeAt(idx);
Loader<Object> loader = info.loader;
if (loader != null) {
loader.unregisterListener(info);
loader.destroy();
}
}
}
}
/**
* Return the Loader with the given id or null if no matching Loader
* is found.
*/
@SuppressWarnings("unchecked")
public <D> Loader<D> getLoader(int id) {
LoaderInfo loaderInfo = mLoaders.get(id);
if (loaderInfo != null) {
return (Loader<D>)mLoaders.get(id).loader;
}
return null;
}
void doStart() {
// Call out to sub classes so they can start their loaders
// Let the existing loaders know that we want to be notified when a load is complete
for (int i = mLoaders.size()-1; i >= 0; i--) {
LoaderInfo info = mLoaders.valueAt(i);
Loader<Object> loader = info.loader;
int id = mLoaders.keyAt(i);
if (loader == null) {
loader = info.callback.onCreateLoader(id, info.args);
info.loader = loader;
}
loader.registerListener(id, info);
loader.startLoading();
}
mStarted = true;
}
void doStop() {
for (int i = mLoaders.size()-1; i >= 0; i--) {
LoaderInfo info = mLoaders.valueAt(i);
Loader<Object> loader = info.loader;
if (loader == null) {
continue;
}
// Let the loader know we're done with it
loader.unregisterListener(info);
// The loader isn't getting passed along to the next instance so ask it to stop loading
//if (!getActivity().isChangingConfigurations()) {
// loader.stopLoading();
//}
}
mStarted = false;
}
void doDestroy() {
if (mLoaders != null) {
for (int i = mLoaders.size()-1; i >= 0; i--) {
LoaderInfo info = mLoaders.valueAt(i);
Loader<Object> loader = info.loader;
if (loader == null) {
continue;
}
loader.destroy();
}
}
}
}
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