Question

我找不到自己的错误。

    public class FragmentParsing extends Fragment implements MyTask.OnTaskComplete{

    private ArrayList<String> arrayList=new ArrayList<>();
    private ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, arrayList);
    private ProgressDialog progressDialog = null;
    private static final String url="http://quotes.zennex.ru/api/v3/bash/quotes?sort=time";

    public FragmentParsing() {
        // Required empty public constructor
    }

//    public static FragmentParsing newInstance() {
//        FragmentParsing fragment = new FragmentParsing();
//        return fragment;
//    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view= inflater.inflate(R.layout.fragment_parsing, container, false);

        ListView lv=(ListView)view.findViewById(R.id.listView);
        lv.setAdapter(adapter);

        progressDialog = ProgressDialog.show(lv.getContext(), null, "Подключение к серверу...", true, true);
        MyTask myTask = new MyTask(FragmentParsing.this);
        myTask.execute(url);

        return view;
    }

    @Override
    public void onTaskComplete(ArrayList<String> array) {
        if(array!=null) {
            adapter.clear();
            arrayList.addAll(array);
            adapter.notifyDataSetChanged();
        }
        else
            Toast.makeText(getView().getContext(), "Сбой при подключение к серверу", Toast.LENGTH_SHORT).show();
        if (progressDialog != null && progressDialog.isShowing()) {
            progressDialog.dismiss();
        }
    }

错误日志：

FATAL EXCEPTION: main
                                                                            Process: ru.bunakov.testapplication, PID: 29433
                                                                            java.lang.NullPointerException
                                                                                at android.widget.ArrayAdapter.init(ArrayAdapter.java:310)
                                                                                at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:153)
                                                                                at ru.bunakov.testapplication.fragments.FragmentParsing.<init>(FragmentParsing.java:20)
                                                                                at ru.bunakov.testapplication.adapters.TabAdapter.getItem(TabAdapter.java:23)

行中有问题 -

private ArrayAdapter<String> adapter = new ArrayAdapter<String(getActivity(), android.R.layout.simple_list_item_1, arrayList);

在这一行 -

case 2: return new FragmentParsing();

这是TabAdapter

    public class TabAdapter extends FragmentStatePagerAdapter {

    private int numberOfTabs;

    public TabAdapter(FragmentManager fm, int numberOfTabs) {
        super(fm);
        this.numberOfTabs = numberOfTabs;
    }

    @Override
    public Fragment getItem(int i) {
        switch (i){
            case 0: return new FragmentList();
            case 1: return new FragmentScaling();
            case 2: return new FragmentParsing();
            case 3: return new FragmentMap();
            default: return null;
        }
    }

    @Override
    public int getCount() {
        return numberOfTabs;
    }
}

我的申请正在关闭我选择不是第一个标签。如果类FragmentParsing为空 - 应用程序没有问题。

编辑：在评论中请求更改后。

    public class FragmentParsing extends Fragment implements MyTask.OnTaskComplete{

    private ArrayList<String> arrayList = new ArrayList<>();
    private ArrayAdapter<String> adapter;
    private ProgressDialog progressDialog = null;
    private static final String url="http://quotes.zennex.ru/api/v3/bash/quotes?sort=time";

    public FragmentParsing() {
        // Required empty public constructor
    }

//    public static FragmentParsing newInstance() {
//        FragmentParsing fragment = new FragmentParsing();
//        return fragment;
//    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view= inflater.inflate(R.layout.fragment_parsing, container, false);

        ListView lv=(ListView)view.findViewById(R.id.listView);


        progressDialog = ProgressDialog.show(lv.getContext(), null, "Подключение к серверу...", true, true);
        MyTask myTask = new MyTask(FragmentParsing.this);
        myTask.execute(url);
        adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, arrayList);
        lv.setAdapter(adapter);
        return view;
    }

错误日志：

FATAL EXCEPTION: main
                                                                            Process: ru.bunakov.testapplication, PID: 12608
                                                                            java.lang.NullPointerException
                                                                                at ru.bunakov.testapplication.fragments.FragmentParsing.onCreateView(FragmentParsing.java:48)

Line - progressDialog = ProgressDialog.show(lv.getContext(), null, "Подключение к серверу...", true, true);

Answer 1

您的adapter似乎已使用导致NullPointerException的空列表进行初始化。简单地把你的

adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, arrayList); lv.setAdapter(adapter);

在

下面的onTaskComplete()内

arrayList.addAll(array);

在初始化适配器之前，列表不再为空。干杯! ：d

在片段中解析。申请已结束

1 个答案: