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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

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SimpleCursorLoader.java
Java
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/*
* Copyright 2012 CodeSlap - Cristian Castiblanco
*
* 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.
*/
 
import android.content.Context;
import android.database.Cursor;
import android.support.v4.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.
*
* This was based on the CursorLoader class
*
* @author cristian
*/
public abstract class SimpleCursorLoader extends AsyncTaskLoader<Cursor> {
private Cursor mCursor;
 
public SimpleCursorLoader(Context context) {
super(context);
}
 
/* Runs on a worker thread */
@Override
public abstract Cursor loadInBackground();
 
/* Runs on the UI thread */
@Override
public void deliverResult(Cursor cursor) {
if (isReset()) {
// An async query came in while the loader is stopped
if (cursor != null) {
cursor.close();
}
return;
}
Cursor oldCursor = mCursor;
mCursor = cursor;
 
if (isStarted()) {
super.deliverResult(cursor);
}
 
if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
oldCursor.close();
}
}
 
/**
* Starts an asynchronous load of the contacts list data. When the result is ready the callbacks
* will be called on the UI thread. If a previous load has been completed and is still valid
* the result may be passed to the callbacks immediately.
* <p/>
* Must be called from the UI thread
*/
@Override
protected void onStartLoading() {
if (mCursor != null) {
deliverResult(mCursor);
}
if (takeContentChanged() || mCursor == null) {
forceLoad();
}
}
 
/**
* Must be called from the UI thread
*/
@Override
protected void onStopLoading() {
// Attempt to cancel the current load task if possible.
cancelLoad();
}
 
@Override
public void onCanceled(Cursor cursor) {
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
}
 
@Override
protected void onReset() {
super.onReset();
 
// Ensure the loader is stopped
onStopLoading();
 
if (mCursor != null && !mCursor.isClosed()) {
mCursor.close();
}
mCursor = null;
}
}

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