集合的Java8 IntStream不兼容的返回类型< Integer> .stream（） [英] Java8 IntStream incompatible return type for Collections<Integer>.stream()

问题描述

我有点迷失了。我有一个代码（我没写），它有一个名为BitSetExt的类，它扩展了BitSet。签名如下所示：

I'm a bit lost with this. I have code (that I didn't write) which has a class called BitSetExt, which extends BitSet. The signature looks like:

private class BitSetExt extends BitSet implements Set<Integer>

在扩展类中不会覆盖stream（）方法。我知道代码编译与Java 1.6完全一致。在使用Java8的Eclipse中，我收到错误：

The stream() method is not overridden in the extended class. I do know that the code compiles just fine with Java 1.6. In Eclipse with Java8, I get the error:

返回类型与继承的方法Collection.stream（），BitSet.stream（）不兼容。

The return types are incompatible for the inherited methods Collection.stream(), BitSet.stream().

如果我尝试覆盖stream（）并将IntStream返回类型更改为任何内容，我会得到一个不同的错误，并建议将返回类型更改为IntStream（显然不兼容） ）。那么，我不理解什么以及如何修复此代码？

If I attempt to override stream() and change the IntStream return type to anything, I get a different error and a suggestion to change the return type to IntStream (which apparently isn't compatible). So, what am I not understanding and how can I fix this code?

感谢您的帮助。

推荐答案

从Java 8开始，BitSet的方法声明为

Since Java 8, BitSet has a method declared as

IntStream stream()

和设置<整数> 有一个方法同名，声明为

and Set<Integer> has a method with the same name, declared as

Stream<Integer> stream()

由于这些方法具有相同的名称但返回类型不兼容，因此无法扩展BitSet并且同时实现Set。

Since those methods have the same name but an incompatible return type, it's impossible to extend BitSet and implement Set at the same time.

你必须重构该类，以便它不实现 Set< Integer> 以及，例如，添加一个方法，在对象上返回视图，实现 Set< Integer> ：

You'll have to refactor the class so that it doesn't implement Set<Integer> anymore and, for example, add a method which returns a view over the object, implementing Set<Integer>:

public Set<Integer> asSet();

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