Question

我要在我的片段上放一些（测试）listview，但应用程序立即崩溃了。这是代码。

public class ListPassword extends Fragment {

private String accountID , masterUsername;
private ListView lv;
private TextView masterUsernameTXT;
private String[][] showingData;
String[] title = { "a" , "b" , "c" , "d" , "e" };
String[] description = { "aaa" , "bbb" , "ccc" , "ddd" , "eee" };
String[] updateDate = { "000" , "111" , "222" , "333" , "444" };
int recordRow = 0;

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

public ListPassword() { }

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_listpassword, container, false);

    String[] title = { "a" , "b" , "c" , "d" , "e" };
    String[] description = { "aaa" , "bbb" , "ccc" , "ddd" , "eee" };
    String[] updateDate = { "000" , "111" , "222" , "333" , "444" };

    lv = (ListView)rootView.findViewById(R.id.listview_password);
    SpinnerAdapt adapter = new SpinnerAdapt(getActivity(),title, description, updateDate);
    lv.setAdapter(adapter);

    return rootView;
}

我尝试通过阅读logcat来解决它，并发现以下错误。

致命的例外：主要处理：com.example.new_ang_ja_kai_la.masterpassword，PID：21591 java.lang.NullPointerException：尝试调用虚方法＆＃39; void android.widget.TextView.setText（java.lang.CharSequence中）＆＃39;在null 对象参考在com.example.new_ang_ja_kai_la.masterpassword.SpinnerAdapt.getCustomView（SpinnerAdapt.java:63）

并且SpinnerAdapt如下（我从我的朋友那里得到了这个）

public class SpinnerAdapt extends BaseAdapter {

    private Activity activity;
    private String[] title;
    private String[] description;
    private String[] updateDate;
    //
    public SpinnerAdapt(Activity activity, String[] title, String[] description, String[] updateDate) {
        this.activity = activity;
        this.title = title;
        this.description = description;
        this.updateDate = updateDate;
    }

    @Override
    public int getCount() {
        return title.length;
    }

    @Override
    public Object getItem(int i) {
        return i;
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        return getCustomView(i, view, viewGroup);
    }

    public View getCustomView(int position, View convertView, ViewGroup parent) {

        holder holder;
        if (convertView == null) {
//            LayoutInflater inflater = (activity).getLayoutInflater();
            LayoutInflater inflater = (LayoutInflater)activity.getSystemService
                    (Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.item_listview_storedpassword,null);
            holder = new holder(convertView);
            convertView.setTag(holder);

        } else {
            holder = (holder) convertView.getTag();
        }
        holder.rowTitle.setText(title[position]);
        holder.rowDescription.setText(description[position]);
        holder.rowUpdateDate.setText(updateDate[position]);
        return convertView;
    }
    public class holder{
        private TextView rowTitle;
        private TextView rowDescription;
        private TextView rowUpdateDate;
        public holder(View v){
            TextView rowTitle= (TextView) v.findViewById(R.id.passwordTitle);
            TextView rowDescription = (TextView) v.findViewById(R.id.passwordDescription);
            TextView rowUpdateDate = (TextView) v.findViewById(R.id.passwordDescription);
        }
    }

}

我调试了这个。它说......

错误发生在＆＃34; lv = （ListView的）rootView.findViewById（R.id.listview_password）;＆＃34;

它表明，当调试完成时，lv的值为null。

我不知道如何解决它，因为我已经检查过R.id.listview_password是正确的引用（通过ctrl +点击它）所以，我可以把指针放好。

我已经检查了解决方案，但没有什么可以帮助我。

Answer 1

您可以在错误消息中看到您的应用在SpinnerAdapter类的第63行崩溃。所以请发布这个课程的代码，以便我们为您提供帮助。

编辑：在没有持有人的情况下尝试：

if (convertView == null) {
    LayoutInflater inflater = LayoutInflater.from(activity);
    convertView = inflater.inflate(R.layout.item_listview_storedpassword, parent, false);
}

TextView rowTitle= (TextView) convertView.findViewById(R.id.passwordTitle);
TextView rowDescription = (TextView) convertView.findViewById(R.id.passwordDescription);
TextView rowUpdateDate = (TextView) convertView.findViewById(R.id.passwordDescription);

if(rowTitle != null) rowTitle.setText(title[position]);
if(rowDescription != null) rowDescription.setText(description[position]);
if(rowUpdateDate != null) rowUpdateDate.setText(updateDate[position]);

return convertView;

＆＃39; void android.widget.TextView.setText（java.lang.CharSequence）＆＃39;在null对象引用上

1 个答案: