RetainFragment.java

/*
 * Copyright (C) 2012 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 com.mzeat.image;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;

/**
 * A simple non-UI Fragment that stores a single Object and is retained over
 * configuration changes. In this sample it will be used to retain the
 * ImageCache object.
 */
public class RetainFragment extends Fragment {
	private static final String TAG = "RetainFragment";
	private Object mObject;

	/**
	 * Empty constructor as per the Fragment documentation
	 */
	public RetainFragment() {
	}

	/**
	 * Locate an existing instance of this Fragment or if not found, create and
	 * add it using FragmentManager.
	 * 
	 * @param fm
	 *            The FragmentManager manager to use.
	 * @return The existing instance of the Fragment or the new instance if just
	 *         created.
	 */
	public static RetainFragment findOrCreateRetainFragment(FragmentManager fm) {
		// Check to see if we have retained the worker fragment.
		RetainFragment mRetainFragment = (RetainFragment) fm
				.findFragmentByTag(TAG);

		// If not retained (or first time running), we need to create and add
		// it.
		if (mRetainFragment == null) {
			mRetainFragment = new RetainFragment();
			fm.beginTransaction().add(mRetainFragment, TAG).commit();
		}

		return mRetainFragment;
	}

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		// Make sure this Fragment is retained over a configuration change
		setRetainInstance(true);
	}

	/**
	 * Store a single object in this Fragment.
	 * 
	 * @param object
	 *            The object to store
	 */
	public void setObject(Object object) {
		mObject = object;
	}

	/**
	 * Get the stored object.
	 * 
	 * @return The stored object
	 */
	public Object getObject() {
		return mObject;
	}

}