HeadlinesFragment.java

/*
 * Copyright (C) 2011 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.example.android.newsreader;

import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

/**
 * Fragment that displays the news headlines for a particular news category.
 *
 * This Fragment displays a list with the news headlines for a particular news category.
 * When an item is selected, it notifies the configured listener that a headlines was selected.
 */
public class HeadlinesFragment extends ListFragment implements OnItemClickListener {
    // The list of headlines that we are displaying
    List<String> mHeadlinesList = new ArrayList<String>();

    // The list adapter for the list we are displaying
    ArrayAdapter<String> mListAdapter;

    // The listener we are to notify when a headline is selected
    OnHeadlineSelectedListener mHeadlineSelectedListener = null;

    /**
     * Represents a listener that will be notified of headline selections.
     */
    public interface OnHeadlineSelectedListener {
        /**
         * Called when a given headline is selected.
         * @param index the index of the selected headline.
         */
        public void onHeadlineSelected(int index);
    }

    /**
     * Default constructor required by framework.
     */
    public HeadlinesFragment() {
        super();
    }

    @Override
    public void onStart() {
        super.onStart();
        setListAdapter(mListAdapter);
        getListView().setOnItemClickListener(this);
        loadCategory(0);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mListAdapter = new ArrayAdapter<String>(getActivity(), R.layout.headline_item,
                mHeadlinesList);
    }

    /**
     * Sets the listener that should be notified of headline selection events.
     * @param listener the listener to notify.
     */
    public void setOnHeadlineSelectedListener(OnHeadlineSelectedListener listener) {
        mHeadlineSelectedListener = listener;
    }

    /**
     * Load and display the headlines for the given news category.
     * @param categoryIndex the index of the news category to display.
     */
    public void loadCategory(int categoryIndex) {
        mHeadlinesList.clear();
        int i;
        NewsCategory cat = NewsSource.getInstance().getCategory(categoryIndex);
        for (i = 0; i < cat.getArticleCount(); i++) {
            mHeadlinesList.add(cat.getArticle(i).getHeadline());
        }
        mListAdapter.notifyDataSetChanged();
    }

    /**
     * Handles a click on a headline.
     *
     * This causes the configured listener to be notified that a headline was selected.
     */
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        if (null != mHeadlineSelectedListener) {
            mHeadlineSelectedListener.onHeadlineSelected(position);
        }
    }

    /** Sets choice mode for the list
     *
     * @param selectable whether list is to be selectable.
     */
    public void setSelectable(boolean selectable) {
        if (selectable) {
            getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        }
        else {
            getListView().setChoiceMode(ListView.CHOICE_MODE_NONE);
        }
    }
}