AbstractSingleDataInstanceAsyncTaskLoader.java

/**
 * The MIT License (MIT)

Copyright (c) 2013 Chute

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package com.getchute.android.photopickerplus.loaders;

import android.content.Context;
import android.support.v4.content.AsyncTaskLoader;
import android.util.Log;

/**
 * An abstract class that performs asynchronous data loading. While Loaders are
 * active they should monitor the source of their data and deliver new results
 * when the contents change.
 * 
 * @author darko.grozdanovski
 * @param <D>
 */
public abstract class AbstractSingleDataInstanceAsyncTaskLoader<D> extends
		AsyncTaskLoader<D> {

	private D data;

	public AbstractSingleDataInstanceAsyncTaskLoader(Context context) {
		super(context);

	}

	public static final String TAG = AbstractSingleDataInstanceAsyncTaskLoader.class
			.getSimpleName();

	@Override
	public void deliverResult(D data) {
		if (isReset()) {
			/*
			 * An asynchronous query came in while the loader is stopped. The
			 * result is not needed.
			 */
			if (data != null) {
				onReleaseResources(data);
			}
		}
		this.data = data;
		if (isStarted()) {
			/*
			 * If the Loader is currently started, the results can be delivered
			 * immediately.
			 */
			super.deliverResult(data);
		}

	}

	public void changeStoredResources(D data) {
		this.data = data;
	}

	public D getData() {
		return data;
	}

	private void onReleaseResources(D data) {
		// TODO Auto-generated method stub
	}

	/**
	 * Handles a request to start the Loader.
	 */
	@Override
	protected void onStartLoading() {
		if (data != null) {
			/*
			 * If the result is currently available, it should be delivered
			 * immediately.
			 */
			deliverResult(data);
		}

		if (takeContentChanged() || data == null) {
			// If the data has changed since the last time it was loaded
			// or is not currently available, start a load.
			forceLoad();
		}
	}

	@Override
	public void forceLoad() {
		Log.d(TAG, "forcing load");
		super.forceLoad();
	}

	/**
	 * Handles a request to stop the Loader.
	 */
	@Override
	protected void onStopLoading() {
		/* Attempt to cancel the current load task if possible. */
		cancelLoad();
	}

	@Override
	public void onCanceled(D data) {
		super.onCanceled(data);
		onReleaseResources(data);
	}

	/**
	 * Handles a request to completely reset the Loader.
	 */
	@Override
	protected void onReset() {
		super.onReset();

		/* Ensure the loader is stopped */
		onStopLoading();

		/*
		 * At this point we can release the resources associated with 'apps' if
		 * needed.
		 */
		if (data != null) {
			onReleaseResources(data);
			data = null;
		}
	}
}