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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.newsreader;
     18 
     19 import android.os.Bundle;
     20 import android.support.v4.app.ListFragment;
     21 import android.view.View;
     22 import android.widget.AdapterView;
     23 import android.widget.AdapterView.OnItemClickListener;
     24 import android.widget.ArrayAdapter;
     25 import android.widget.ListView;
     26 
     27 import java.util.ArrayList;
     28 import java.util.List;
     29 
     30 /**
     31  * Fragment that displays the news headlines for a particular news category.
     32  *
     33  * This Fragment displays a list with the news headlines for a particular news category.
     34  * When an item is selected, it notifies the configured listener that a headlines was selected.
     35  */
     36 public class HeadlinesFragment extends ListFragment implements OnItemClickListener {
     37     // The list of headlines that we are displaying
     38     List<String> mHeadlinesList = new ArrayList<String>();
     39 
     40     // The list adapter for the list we are displaying
     41     ArrayAdapter<String> mListAdapter;
     42 
     43     // The listener we are to notify when a headline is selected
     44     OnHeadlineSelectedListener mHeadlineSelectedListener = null;
     45 
     46     /**
     47      * Represents a listener that will be notified of headline selections.
     48      */
     49     public interface OnHeadlineSelectedListener {
     50         /**
     51          * Called when a given headline is selected.
     52          * @param index the index of the selected headline.
     53          */
     54         public void onHeadlineSelected(int index);
     55     }
     56 
     57     /**
     58      * Default constructor required by framework.
     59      */
     60     public HeadlinesFragment() {
     61         super();
     62     }
     63 
     64     @Override
     65     public void onStart() {
     66         super.onStart();
     67         setListAdapter(mListAdapter);
     68         getListView().setOnItemClickListener(this);
     69         loadCategory(0);
     70     }
     71 
     72     @Override
     73     public void onCreate(Bundle savedInstanceState) {
     74         super.onCreate(savedInstanceState);
     75         mListAdapter = new ArrayAdapter<String>(getActivity(), R.layout.headline_item,
     76                 mHeadlinesList);
     77     }
     78 
     79     /**
     80      * Sets the listener that should be notified of headline selection events.
     81      * @param listener the listener to notify.
     82      */
     83     public void setOnHeadlineSelectedListener(OnHeadlineSelectedListener listener) {
     84         mHeadlineSelectedListener = listener;
     85     }
     86 
     87     /**
     88      * Load and display the headlines for the given news category.
     89      * @param categoryIndex the index of the news category to display.
     90      */
     91     public void loadCategory(int categoryIndex) {
     92         mHeadlinesList.clear();
     93         int i;
     94         NewsCategory cat = NewsSource.getInstance().getCategory(categoryIndex);
     95         for (i = 0; i < cat.getArticleCount(); i++) {
     96             mHeadlinesList.add(cat.getArticle(i).getHeadline());
     97         }
     98         mListAdapter.notifyDataSetChanged();
     99     }
    100 
    101     /**
    102      * Handles a click on a headline.
    103      *
    104      * This causes the configured listener to be notified that a headline was selected.
    105      */
    106     @Override
    107     public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
    108         if (null != mHeadlineSelectedListener) {
    109             mHeadlineSelectedListener.onHeadlineSelected(position);
    110         }
    111     }
    112 
    113     /** Sets choice mode for the list
    114      *
    115      * @param selectable whether list is to be selectable.
    116      */
    117     public void setSelectable(boolean selectable) {
    118         if (selectable) {
    119             getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    120         }
    121         else {
    122             getListView().setChoiceMode(ListView.CHOICE_MODE_NONE);
    123         }
    124     }
    125 }
    126