setText方法上的android studio java NullPointerException

我有一个问题，从昨天开始一直在搜索，我发布代码：

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_show_wishes);

    mListView = (ListView) findViewById(R.id.listId);

    refreshData();

}

private void refreshData() {

    wishes.clear();

    dbHandler = new DatabaseHandler(getApplicationContext());

    ArrayList<MyWishes> wishesFromDB = dbHandler.getWishes();

    for (int i = 0; i < wishesFromDB.size(); i++){

        String title = wishesFromDB.get(i).getTitle();
        String content = wishesFromDB.get(i).getContent();
        String date = wishesFromDB.get(i).getRecordDate();

        MyWishes myWishes = new MyWishes();

        myWishes.setTitle(title);
        myWishes.setContent(content);
        myWishes.setRecordDate(date);

        wishes.add(myWishes);

    }

    dbHandler.close();

    mWishAdapter = new WishAdapter(showWishesActivity.this, R.layout.list_row, wishes);
    mListView.setAdapter(mWishAdapter);
    mWishAdapter.notifyDataSetChanged();
}

public class WishAdapter extends ArrayAdapter<MyWishes>{

    Activity activity;
    MyWishes wish;
    ArrayList<MyWishes> mData = new ArrayList<>();
    int layoutRessource;

    public WishAdapter(Activity act, int resource, ArrayList<MyWishes> data) {
        super(act, resource, data);
        activity = act;
        layoutRessource = resource;
        mData = data;
        notifyDataSetChanged();
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public int getPosition(MyWishes item) {
        return super.getPosition(item);
    }

    @Nullable
    @Override
    public MyWishes getItem(int position) {
        return mData.get(position);
    }

    @Override
    public long getItemId(int position) {
        return super.getItemId(position);
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View row = convertView;
        ViewHolder holder = null;

        if (row == null || (row.getTag()) == null){

            LayoutInflater inflater = LayoutInflater.from(activity);
            row = inflater.inflate(layoutRessource, null);

            holder = new ViewHolder();

            holder.mTitle = (TextView) findViewById(R.id.titre);
            holder.mDate = (TextView) findViewById(R.id.date);

            row.setTag(holder);
        }else {

            holder = (ViewHolder) row.getTag();
        }

        holder.mMyWishes = getItem(position);

        holder.mTitle.setText(holder.mMyWishes.getTitle());
        holder.mDate.setText(holder.mMyWishes.getRecordDate());

        return row;
    }

    class ViewHolder{

        MyWishes mMyWishes;
        TextView mTitle;
        TextView mContent;
        TextView mDate;
        TextView mId;
    }
}

我不明白这个问题，任何人都可以帮我，谢谢你的时间。

而不是这个

holder.mTitle = (TextView) findViewById(R.id.titre);

试试这个

holder.mTitle = (TextView) convertView.findViewById(R.id.titre);

---

您的视图未在

getView

中初始化。因此：

删除此项：

        holder.mTitle = (TextView) findViewById(R.id.titre);
        holder.mDate = (TextView) findViewById(R.id.date);

为此：

        holder.mTitle = (TextView) row.findViewById(R.id.titre);
        holder.mDate = (TextView) row.findViewById(R.id.date);

---

在您的getView中，请使用以下命令：

    holder.mTitle = (TextView)row.findViewById(R.id.titre);


    holder.mDate = (TextView)row.findViewById(R.id.date);

---

您错过了要参考的视图

listview

将每个项目替换为指定的布局

然后在

listview

项的返回视图中使用

getview

方法

你可以用like

holder.mTitle = (TextView) row.findViewById(R.id.titre);

行是布局的视图

 @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View row = convertView;
        ViewHolder holder = null;

        if (row == null || (row.getTag()) == null){

            LayoutInflater inflater = LayoutInflater.from(activity);
            row = inflater.inflate(layoutRessource, null);
            holder = new ViewHolder();

            holder.mTitle = (TextView) row.findViewById(R.id.titre);
            holder.mDate = (TextView) row.findViewById(R.id.date);

            row.setTag(holder);
        }else {

            holder = (ViewHolder) row.getTag();
        }

        holder.mMyWishes = getItem(position);

        holder.mTitle.setText(holder.mMyWishes.getTitle());
        holder.mDate.setText(holder.mMyWishes.getRecordDate());

        return row;
    }

    class ViewHolder{

        MyWishes mMyWishes;
        TextView mTitle;
        TextView mContent;
        TextView mDate;
        TextView mId;
    }

    holder.mTitle = (TextView)row.findViewById(R.id.titre);


    holder.mDate = (TextView)row.findViewById(R.id.date);

holder.mTitle = (TextView) row.findViewById(R.id.titre);

 @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View row = convertView;
        ViewHolder holder = null;

        if (row == null || (row.getTag()) == null){

            LayoutInflater inflater = LayoutInflater.from(activity);
            row = inflater.inflate(layoutRessource, null);
            holder = new ViewHolder();

            holder.mTitle = (TextView) row.findViewById(R.id.titre);
            holder.mDate = (TextView) row.findViewById(R.id.date);

            row.setTag(holder);
        }else {

            holder = (ViewHolder) row.getTag();
        }

        holder.mMyWishes = getItem(position);

        holder.mTitle.setText(holder.mMyWishes.getTitle());
        holder.mDate.setText(holder.mMyWishes.getRecordDate());

        return row;
    }

    class ViewHolder{

        MyWishes mMyWishes;
        TextView mTitle;
        TextView mContent;
        TextView mDate;
        TextView mId;
    }