java - 为什么我们不在 bindView 中使用 moveToFirst()？

Question

实现时onLoadFinished() , 它需要 moveToFirst()运行良好，但为什么在实现 bindView() 时不需要这样做？对于 CursorAdapter ?以及何时使用它？
onLoadFinished:

@Override
public void onLoadFinished(@NonNull Loader loader, Cursor data) {
    if (data.moveToFirst()) {
        int nameColumnIndex = data.getColumnIndexOrThrow(PetEntry.COLUMN_PET_NAME);
        int breedColumnIndex = data.getColumnIndexOrThrow(PetEntry.COLUMN_PET_BREED);

        mNameEditText.setText(data.getString(nameColumnIndex));
        mBreedEditText.setText(data.getString(breedColumnIndex));

    }
}

绑定(bind) View :

@Override
public void bindView(View view, Context context, Cursor cursor) {
    TextView name = view.findViewById(R.id.name);
    TextView summary = view.findViewById(R.id.summary);

    String nameString = cursor.getString(cursor.getColumnIndexOrThrow(PetEntry.COLUMN_PET_NAME));
    String summaryString = cursor.getString(cursor.getColumnIndexOrThrow(PetEntry.COLUMN_PET_BREED));

    name.setText(nameString);
    summary.setText(summaryString);
}

Answer 1

该 API 在 CursorAdapter.bindView 中明确声明:@param cursor The cursor from which to get the data. The cursor is already moved to the correct position.所以moveToFirst已经为你完成了。需要该操作来推进从数据库查询返回的记录。如果没有找到记录，则 moveToFirst 将根据 API 描述返回 false:Move the cursor to the first row. This method will return false if the cursor is empty.onLoadFinished 不是 CursorAdapter 的成员，因此不适合这样做。
问候，迈克