为什么这项任务不起作用？ [英] Why wont this assignment work?

问题描述

我有一个结果，其中扩展了ArrayList< Results> 。我有一个对象 i ，它有一个函数 i.getResults（），它返回一个 ArrayList ，类型为 ArrayList< Results> 。我正在尝试以下方法：

I've got a class Results which extends ArrayList<Results>. I've got an object i which has a function i.getResults() which returns an ArrayList of type ArrayList<Results>. I'm attempting the following:

Results result = i.getResults();

但是，我遇到类型不匹配错误。为什么我不能做这个任务？如何将其分配到类型结果？

However, I'm getting a type mismatch error. Why can't I make this assignment? How can I assign it to type Results?

编辑：要解释我正在尝试实现的目标..我无法访问到 ArrayList< Results> 代码，我想让它实现某个类，我有结果实现

To explain what I'm trying to achieve.. I don't have access to the ArrayList<Results> code and I'd like to make it implement a certain class which I have Results implementing

推荐答案

你不能 - ArrayList< Results> 不是a 结果。 结果是一个 ArrayList< Results> 但是，您可以另外指定。

You can't - ArrayList<Results> isn't a Results. Results is an ArrayList<Results> though, you could assign the other way.

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