com.lkunic.lib.activityaddonlib.twopane.fragments.ItemListFragment.java Source code

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/**********************************************************************
 * Copyright (c) 2015 Luka Kunic, "ItemListFragment.java"
 * 
 * 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.
 *
 * Author: lkunic
 * Last modified: 16/01/2015
 **********************************************************************/
package com.lkunic.lib.activityaddonlib.twopane.fragments;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;

import com.lkunic.lib.activityaddonlib.R;

/**
 * A list fragment representing a list of Items.
 * Activities containing this fragment MUST implement the {@link Callbacks} interface.
 */
public abstract class ItemListFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_item_list, container, false);

        // Setup the item list
        ListView list = (ListView) view.findViewById(R.id.item_list);
        list.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                mCallbacks.onItemSelected(id);
            }
        });

        // Call to the abstract method that is used by a derived class to add content to the list
        setupListContent(list);

        return view;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // Activities containing this fragment must implement its callback
        if (!(activity instanceof Callbacks)) {
            throw new IllegalStateException(
                    String.format("%s must implement fragment's callbacks.", activity.getClass().getName()));
        }

        mCallbacks = (Callbacks) activity;
    }

    @Override
    public void onDetach() {
        super.onDetach();

        // Reset the active callback interface to the dummy implementation
        mCallbacks = sDummyCallbacks;
    }

    /**************************************************************************************************/
    /**** Abstract methods ****/
    /**************************************************************************************************/

    /**
     * Implement to set up list adapter and content. You can extend the ItemListCursorAdapter and use
     * it for populating your list using a cursor.
     */
    protected abstract void setupListContent(View list);

    /**************************************************************************************************/
    /**** Callback implementation ****/
    /**************************************************************************************************/

    // The fragment's current callback object, which is notified of list item clicks
    private Callbacks mCallbacks = sDummyCallbacks;

    /**
     * A callback interface that all activities containing this fragment must implement. This mechanism allows
     * activities to be notified of item selections.
     */
    public interface Callbacks {
        /**
         * Callback for when an item has been selected.
         */
        public void onItemSelected(long id);
    }

    /**
     * Returns the callback object.
     * @return
     */
    protected Callbacks getCallbacks() {
        return mCallbacks;
    }

    /**
     * A dummy implementation of the {@link Callbacks} interface that does
     * nothing. Used only when this fragment is not attached to an activity.
     */
    private static Callbacks sDummyCallbacks = new Callbacks() {
        @Override
        public void onItemSelected(long id) {
            Log.e("ItemListFragment", "Dummy callback method called. Something is wrong with the implementation");
        }
    };
}