java8中，逻辑与 & 符号用在接口类上代表什么意思

转载于 2018-10-18 00:18:35 发布 · 652 阅读

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本文探讨了Java中Comparator接口的comparingInt方法使用细节，特别是如何利用Lambda表达式和类型强转实现串行化的比较器创建。深入解析了方法内部的Lambda表达式语法和类型强转的作用。

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最近在读lambda表达式相关的java源码，在Comparator的静态方法里发现有不少这种类似的写法
java.util.Comparator
…
public static Comparator comparingInt(ToIntFunction<? super T> keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator & Serializable)
(c1, c2) -> Integer.compare(keyExtractor.applyAsInt(c1), keyExtractor.applyAsInt(c2));
}

其中return (Comparator & Serializable)应该是表示类型强转

The part I’m interested in is this: return (Comparator & Serializable):

This means that the resulting value will be cast to Comparator and Serializable (i.e. a serializable comparator)

Note that when doing casts like this one, you’re allowed to specify only one class (and infinite amount of interfaces), because it’s not possible for a class to inherit from more than one super-class.