HashMap和HashMultimap有什么区别 [英] What is difference between HashMap and HashMultimap

问题描述

我看到很多关于multimap的例子但不明白为什么Google Gauva与众不同？

I see many examples about multimap but did not understand why Google Gauva is different?

Multimap<Integer, Set<String>> option4 = HashMultimap.create(); // Gauva

Map<Integer, Set<String>> opt = new HashMap<Integer, Set<String>>(); //Core Java

以上两者对于保存数据的行为是否相同或不同？

Is both above are behave same for holding data or different?

推荐答案

A MultiMap< A，B> 关联类型的键A的值为 Collection< B> （因此名称为MultiMap）

A MultiMap<A, B> associates a key of type A with a value of type Collection<B> (hence the name MultiMap)

A Map< A，B> 将类型A的键与类型B的值相关联。

A Map<A, B> associates a key of type A with a value of type B.

所以， MultiMap< Integer，Set< String>> 可以被视为 Map< Integer，Collection< Set< String>> 。这应该是显而易见的，阅读 api文档。

So, a MultiMap<Integer, Set<String>> can be viewed as a Map<Integer, Collection<Set<String>>. This should be obvious by reading the api documentation.

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