在Java中实例化集合集？ [英] Instantiating Set of Sets in Java?

问题描述

我想实例化一组（字符串），然后将两个 Set< String> 放入其中，如下所示：

I want to instantiate a Set of Sets (of strings), and then place two Set<String>'s into it, like below:

Set<String> setOne = retrieveSetOne();
Set<String> setTwo = retrieveSetTwo();
Set<Set<String>> myCollection = new HashSet<new HashSet<String<()>(); // not working
myCollection.add(setOne);
myCollection.add(setTwo);

问题是，我对嵌套集的实例化不起作用。我该怎么做？

Problem is, my instantiation of the nested set does not work. How do I do this?

推荐答案

将其更改为

Set<Set<String>> myCollection = new HashSet<Set<String>>();

在创建实例时通过实现初始化，对于需要匹配声明的类型，

you initialize by implementation when you create instance, for type you need to match declaration,

如果您已经使用Java7，那么您只需使用

If you are on Java7 already then you can simply use

Set<Set<String>> myCollection = new HashSet<>();

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