Fragment 中的 ArrayAdapter - Android

Posted 2023-04-19

【中文标题】Fragment 中的 ArrayAdapter - Android

【英文标题】：ArrayAdapter in Fragment - Android

【发布时间】：2014-11-13 08:55:08

【问题描述】：

我收到一些错误，我不知道为什么。我正在使用片段中的字符串中的数组适配器填充 ListView。我使用这个片段作为主屏幕显示在主要活动中 这是我的代码

public class HomePage extends Fragment 

private ListView lvHomePage;
private String[] items;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
    View view = inflater.inflate(R.layout.fragment_home_page, container, false);

    items = getActivity().getResources().getStringArray(R.array.test);
    lvHomePage = (ListView) getActivity().findViewById(R.id.lvHomePage);

    lvHomePage.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(),
    android.R.layout.simple_list_item_1 , items));

    return view;

我得到这个输出错误：

09-18 21:07:27.315: E/AndroidRuntime(3839): FATAL EXCEPTION: main
09-18 21:07:27.315: E/AndroidRuntime(3839): Process: com.kiko.bmgu.crnobelo, PID: 3839
09-18 21:07:27.315: E/AndroidRuntime(3839): java.lang.RuntimeException: Unable to start activity ComponentInfo     com.kiko.bmgu.crnobelo/com.kiko.bmgu.crnobelo.activities.MainActivity: java.lang.NullPointerException
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)\
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.os.Handler.dispatchMessage(Handler.java:102)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.os.Looper.loop(Looper.java:136)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.ActivityThread.main(ActivityThread.java:5017)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at java.lang.reflect.Method.invokeNative(Native Method)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at java.lang.reflect.Method.invoke(Method.java:515)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at dalvik.system.NativeStart.main(Naive Method)
09-18 21:07:27.315: E/AndroidRuntime(3839): Caused by: java.lang.NullPointerException
09-18 21:07:27.315: E/AndroidRuntime(3839):     at com.kiko.bmgu.fragments.HomePage.onCreateView(HomePage.java:25)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.Fragment.performCreateView(Fragment.java:1700)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.BackStackRecord.run(BackStackRecord.java:684)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.Activity.performStart(Activity.java:5240)
09-18 21:07:27.315: E/AndroidRuntime(3839):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)
09-18 21:07:27.315: E/AndroidRuntime(3839):     ... 11 more

【参考方案1】：

试试这个方法

 private ListView lvHomePage;
    private String[] items;
    private View view;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
    View view = inflater.inflate(R.layout.fragment_home_page, container, false);

    return view;


@Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) 
        super.onActivityCreated(savedInstanceState);

    items = view.getResources().getStringArray(R.array.test);
    lvHomePage = (ListView) view.findViewById(R.id.lvHomePage);

    lvHomePage.setAdapter(new ArrayAdapter<String>(view.getContext(),
    android.R.layout.simple_list_item_1 , items));
   ...

【讨论】：

正如 AIL 所说，我应该使用 view 而不是 getActivity()

【参考方案2】：

lvHomePage 必须为空。请改用lvHomePage = (ListView) view.findViewById(R.id.lvHomePage);。

【参考方案3】：

问题在lvHomePage = (ListView) getActivity().findViewById(R.id.lvHomePage);内 错了，你应该得到根视图是view 而不是活动 所以应该是这样的

lvHomePage = (ListView) view.findViewById(R.id.lvHomePage);