de.zell.android.util.fragments.EntityListFragment.java Source code

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Here is the source code for de.zell.android.util.fragments.EntityListFragment.java

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/*
 * Copyright (C) 2015 Christopher Zell <zelldon91@googlemail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package de.zell.android.util.fragments;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.ListView;
import de.zell.android.util.activities.ViewFragmentBroadcaster;
import de.zell.android.util.adapters.EntityListAdapter;
import de.zell.android.util.db.Entity;
import java.util.Arrays;
import java.util.List;

/**
 * Represents an abstract EntityListFragment which provides some list fragment
 * functionality and also defines some methods to create a good looking
 * sectional list fragment.
 *
 * @author Christopher Zell <zelldon91@googlemail.com>
 */
public abstract class EntityListFragment extends ListFragment implements Nameable {

    /**
     * The argument key for the entity url.
     */
    public static final String ARG_ENTITIES_URL = "entities.url";
    /**
     * The argument key for the entities.
     */
    public static final String ARG_ENTITIES = "entities";
    /**
     * The tag key for the entities content.
     */
    private static final String TAG_ENTITIES_CONTENT = "entities.content";
    /**
     * The index of the current showed entity.
     */
    private int index = -1;
    /**
     * The top of the list view.
     */
    private int top = 0;
    /**
     * The url which identifies the content of the entities.
     */
    private String url;
    /**
     * The list of entities which are showed in the list fragment.
     */
    protected List<Entity> entities = null;

    /**
     * The manager manages the action bar title.
     */
    private ActionBarTitleManager barManager;

    /**
     * Returns the url which identifies the content of the entities. The url is
     * used to download the content.
     *
     * @return the url
     */
    public String getURL() {
        return url;
    }

    @Override
    public void onResume() {
        super.onResume();
        if (index != -1) {
            this.getListView().setSelectionFromTop(index, top);
        }
        ViewFragmentBroadcaster.broadcstViewFragment(getActivity(), getName());
    }

    @Override
    public void onPause() {
        super.onPause();
        index = this.getListView().getFirstVisiblePosition();
        View v = this.getListView().getChildAt(0);
        top = (v == null) ? 0 : v.getTop();
        ViewFragmentBroadcaster.boradcastHideFragment(getActivity());
    }

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

        if (savedInstanceState == null) {
            savedInstanceState = getArguments();
        }

        if (savedInstanceState != null) {
            restoreEntities(savedInstanceState, TAG_ENTITIES_CONTENT);
            EntityListAdapter adapter = getEntityListAdapter(getActivity());
            if (entities == null) {
                restoreEntities(savedInstanceState, ARG_ENTITIES);
                if (entities == null) {
                    url = (String) savedInstanceState.getSerializable(ARG_ENTITIES_URL);
                    loadEntities();
                }
            }
            barManager = new ActionBarTitleManager(savedInstanceState);
            if (entities != null)
                adapter.setEntities(entities);
            setListAdapter(adapter);
        }
    }

    @Override
    public void onStart() {
        super.onStart();
        barManager.setActionBarTitle(getActivity().getActionBar());
    }

    /**
     * Restores the entity list from the given bundle with the given key.
     * 
     * @param savedInstanceState the bundle which should contain the entity array
     * @param key the key which identifies the entity array in the bundle
     */
    private void restoreEntities(Bundle savedInstanceState, String key) {
        Entity[] e = (Entity[]) savedInstanceState.getSerializable(key);
        if (e != null) {
            entities = Arrays.asList(e);
        }
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        Object item = getListAdapter().getItem(position);

        if (item instanceof Entity) {
            onEntityClick(((Entity) item));
        } else {
            onSectionClick(item);
        }
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        barManager.storeTitle(outState);
        if (entities != null)
            outState.putSerializable(TAG_ENTITIES_CONTENT, entities.toArray(new Entity[entities.size()]));
    }

    /**
     * The method is called if the element, which was clicked in the list
     * fragment, was an entity.
     *
     * @param e the entity which was clicked
     */
    protected abstract void onEntityClick(Entity e);

    /**
     * The method is called if the element, which was clicked in the list
     * fragment, was a section.
     *
     * @param o the section which was clicked
     */
    protected abstract void onSectionClick(Object o);

    /**
     * Contains the functionality to load the entities into the current list
     * adapter.
     *
     * Could contain an async task to load the content from a web resource or load
     * content from a database.
     */
    protected abstract void loadEntities();

    /**
     * Returns the EntityListAdapter implementation which should be used for the
     * list fragment.
     *
     * @param ctx the application context
     * @return the list adapter which should be used
     */
    protected abstract EntityListAdapter getEntityListAdapter(Context ctx);
}