如何在 Java 中使用具有重复键的 HashMap？
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How can i have a HashMap in Java with duplicate keys?
提问by programmer
I need a collection in Java that is going to store a pair, a key and a value.
我需要一个 Java 集合来存储一对、一个键和一个值。
So I decided to use a HashMap<String,String>, but I noticed that when I try to add a key that already exists, the previous (key,value) is replaced by the new one (NewKey,NewValue) and the previous entry is lost. So when I have duplicate keys, the previous key is replaced by the new one.
所以我决定使用 a HashMap<String,String>，但我注意到当我尝试添加一个已经存在的键时，之前的 (key,value) 被新的 (NewKey,NewValue) 替换，并且之前的条目丢失了。所以当我有重复的键时，以前的键会被新的键替换。
How can I have a HashMap with duplicate keys?
我怎样才能拥有一个带有重复键的 HashMap？
采纳答案by Eugen Halca
you need MultiMap,
take a look at Google Guava Multimap
你需要MultiMap，看看Google Guava Multimap
回答by Ted Hopp
If you want to map a key to a collection of values, take a look at Guava's Multimap. If you don't want to use a third-party library, you can simulate a Multimapwith a Map<String, Collection<String>>. The Java tutorial on the Mapinterfacehas an example of implementing a Multimap.
如果要将键映射到值集合，请查看 Guava 的Multimap. 如果不想使用第三方库，可以模拟一个Multimap带有Map<String, Collection<String>>. 该上的Java教程Map接口具有实现的一个例子Multimap。
