设置适配器时，它会在片段中给出空指针异常

Question

我是一名新的学习者。我在margin-top: -50%; 遇到了这个空指针异常，因为lListView setAdapter() ListView`并且Adapter不是null。 我附加了我的logcat和fragament，适配器代码。我搜索过互联网，我认为它可能与Fragment有关。

News_Title_fragment：

. Both the

NewsAdapter：

package com.example.fragmentbestpractice;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;

public class NewsTitleFragment extends Fragment implements OnItemClickListener {

    private ListView newsTitleListView;

    private List<News> newsList;

    private NewsAdapter adapter;

    private boolean isTwoPane;

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        newsList = getNews();
        adapter = new NewsAdapter(activity, R.layout.news_item, newsList);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.news_title_frag, container, false);
        newsTitleListView = (ListView) view.findViewById(R.id.news_title_list_view);
        newsTitleListView.setAdapter(adapter);
        newsTitleListView.setOnItemClickListener(this);
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (getActivity().findViewById(R.id.news_content_layout) != null) {
            isTwoPane = true;
        } else {
            isTwoPane = false;
        }
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
        News news = newsList.get(position);
        if (isTwoPane) {
            NewsContentFragment newsContentFragment = (NewsContentFragment) getFragmentManager()
                    .findFragmentById(R.id.news_content_fragment);
            newsContentFragment.refresh(news.getTitle(), news.getContent());
        } else {
            NewsContentActivity.actionStart(getActivity(), news.getTitle(),
                    news.getContent());
        }
    }

    private List<News> getNews() {
        List<News> newsList = new ArrayList<News>();
        News news1 = new News();
        news1.setTitle("Succeed in College as a Learning Disabled Student");
        news1.setContent("College freshmen will soon learn to live with a roommate, adjust to a new social scene and survive less-than-stellar dining hall food. Students with learning disabilities will face these transitions while also grappling with a few more hurdles.");
        newsList.add(news1);
        News news2 = new News();
        news2.setTitle("Google Android exec poached by China's Xiaomi");
        news2.setContent("China's Xiaomi has poached a key Google executive involved in the tech giant's Android phones, in a move seen as a coup for the rapidly growing Chinese smartphone maker.");
        newsList.add(news2);
        return newsList;
    }

}

logcat的：

package com.example.fragmentbestpractice;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class NewsAdapter extends ArrayAdapter<News> {

    private int resourceId;

    public NewsAdapter(Context context, int textViewResourceId, List<News> objects) {
        super(context, textViewResourceId, objects);
        resourceId = textViewResourceId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        News news = getItem(position);
        View view;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, null);
        } else {
            view = convertView;
        }
        TextView newsTitleText = (TextView) view.findViewById(R.id.news_title);
        newsTitleText.setText(news.getTitle());
        return view;
    }

}