在ListFragment的ArrayList中JSON解析throwing getApplicationContext（）錯誤

Question

我正在開發一個應用程序，它在ListFragment中顯示一些基本解析的JSON。 我跟着http://www.androidhive.info/2012/01/android-json-parsing-tutorial，它在ListActivity中工作得很好。然後我開始製作我自己的應用程序。我在Android Studio 1.5中創建了新項目，添加了Navigation Drawer Activity，因爲我有更多的東西要做/顯示並開始將代碼重寫爲片段。這基本上很容易，除了一個瘋狂的問題getApplicationContext()和Cannot resolve method getApplciationContext()錯誤仍然沒有得到解決。

這裏是我的片斷的一部分：

public class Den1Fragment extends ListFragment { 

private ProgressDialog pDialog; 

// JSON Node names 
private static final String TAG_CONTACTS = "contacts"; 
private static final String TAG_ID = "id"; 
private static final String TAG_NAME = "name"; 
private static final String TAG_EMAIL = "email"; 
private static final String TAG_ADDRESS = "address"; 
private static final String TAG_GENDER = "gender"; 
private static final String TAG_PHONE = "phone"; 
private static final String TAG_PHONE_MOBILE = "mobile"; 
private static final String TAG_PHONE_HOME = "home"; 
private static final String TAG_PHONE_OFFICE = "office"; 

// contacts JSONArray 
JSONArray contacts = null; 

// Hashmap for ListView 
ArrayList<HashMap<String, String>> contactList; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    return inflater.inflate(R.layout.fragment_den1, container, false); 

    contactList = new ArrayList<>(); 

    ListView lv = getListView(); 

    // Listview on item click listener 
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, 
           int position, long id) { 
      // getting values from selected ListItem 
      String name = ((TextView) view.findViewById(R.id.name)) 
        .getText().toString(); 
      String cost = ((TextView) view.findViewById(R.id.email)) 
        .getText().toString(); 
      String description = ((TextView) view.findViewById(R.id.mobile)) 
        .getText().toString(); 

      // Starting single contact activity 
      Intent in = new Intent(getApplicationContext(), // TODO error! 
        SingleContactActivity.class); 
      in.putExtra(TAG_NAME, name); 
      in.putExtra(TAG_EMAIL, cost); 
      in.putExtra(TAG_PHONE_MOBILE, description); 
      startActivity(in); 

     } 
    }); 
    // Calling async task to get json 
    new GetContacts().execute(); 
} 

如果我添加Intent in = new Intent(**getActivity().**getApplicationContext(), SingleContactActivity.class);錯誤轉移到contactList = new ArrayList<>();和Android Studio有不知道如何解決它，甚至谷歌搜索並沒有帶來多大的希望的結果。 我試圖用不同的重寫順序再次執行，發現如果我離開setContentView(R.layout.activity_main);而不是將其更改爲return inflater.inflate(R.layout.fragment_den1, container, false);，setContentView將變爲紅色，但contactList行保持「OK」。

編輯

content_main.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin" 
android:paddingBottom="@dimen/activity_vertical_margin" 
android:id="@+id/content_frame" 
app:layout_behavior="@string/appbar_scrolling_view_behavior" 
tools:showIn="@layout/app_bar_main" 
tools:context=".MainActivity"> 

<ListView 
    android:id="@android:id/list" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"/> 
</LinearLayout> 

錯誤報告：

java.lang.RuntimeException: Unable to start activity ComponentInfo{cz.ludato.festapp/cz.ludato.festapp.MainActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 
Caused by: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 
at cz.ludato.festapp.Den1Fragment.onViewCreated(Den1Fragment.java:54) 

Answer 1

試試這個代碼：

public class Den1Fragment extends ListFragment { 

private ProgressDialog pDialog; 

// JSON Node names 
private static final String TAG_CONTACTS = "contacts"; 
private static final String TAG_ID = "id"; 
private static final String TAG_NAME = "name"; 
private static final String TAG_EMAIL = "email"; 
private static final String TAG_ADDRESS = "address"; 
private static final String TAG_GENDER = "gender"; 
private static final String TAG_PHONE = "phone"; 
private static final String TAG_PHONE_MOBILE = "mobile"; 
private static final String TAG_PHONE_HOME = "home"; 
private static final String TAG_PHONE_OFFICE = "office"; 

// contacts JSONArray 
private JSONArray contacts = null; 

// Hashmap for ListView 
private ArrayList<HashMap<String, String>> contactList = new ArrayList<>();; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
View view = inflater.inflate(R.layout.fragment_den1, container, false); 
ListView lv = getListView(); 

// Listview on item click listener 
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

    @Override 
    public void onItemClick(AdapterView<?> parent, View view, 
          int position, long id) { 
     // getting values from selected ListItem 
     String name = ((TextView) view.findViewById(R.id.name)) 
       .getText().toString(); 
     String cost = ((TextView) view.findViewById(R.id.email)) 
       .getText().toString(); 
     String description = ((TextView) view.findViewById(R.id.mobile)) 
       .getText().toString(); 

     Intent in = new Intent(getActivity(), SingleContactActivity.class); 
     in.putExtra(TAG_NAME, name); 
     in.putExtra(TAG_EMAIL, cost); 
     in.putExtra(TAG_PHONE_MOBILE, description); 
     getActivity().startActivity(in); 

    } 
}); 

// Calling async task to get json 
new GetContacts().execute(); 

return view; 
}