我使用 TreeMap 类来存储消息信息及其在应用程序中的优先级。
我使用了 treeMap 类来执行此操作，因为此类会根据键值自动对元素进行排序，例如我有这种情况：
enum Priority { HIGH, MEDIUM, LOW }
TreeMap<Priority,String> tMap = new TreeMap<Priority,String>();
我使用键（消息的优先级）根据优先级严重性自动对消息进行排序，但问题是，在 TreeMap 中，键是唯一的，那么如果我尝试插入具有相同优先级的两条消息，第一个消息将被覆盖......
我如何更改此行为并禁用 TreeMap 上的唯一约束？
是否有像 TreeMap 这样的类允许为多个元素放置相同的 Key？
I use a TreeMap class for store messages information with their priority in my application.
I've used a treeMap class for do it because this class order automatically the element based on the key value, for example i have this situation :
enum Priority { HIGH, MEDIUM, LOW }
TreeMap<Priority,String> tMap = new TreeMap<Priority,String>();
I use the key (priority of the message) for automatically order messages based on the priority severity, but the problem is that in TreeMap the key is unique then if i try to insert two messages with the same priority the first is overwritten ....
How can i change this behaviour and disable unique constraint on TreeMap?
Is there a class like TreeMap that allow to put the same Key for multiple element ?
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你不能。键的唯一性是 Map 接口的基本不变性。
您可以将其实现为
Map> 并自行管理列表。如果（例如）您想要按先进先出顺序处理给定优先级的消息，这是一个不错的选择。或者，您可以使用 MultiMap 类；例如来自 Apache 公共集合 或 < a href="http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/collect/Multimap.html" rel="noreferrer">番石榴。
You can't. The uniqueness of keys is a fundamental invariant of the
Mapinterface.You can implement this as a
Map<Priority,List<String>>and manage the lists yourself. This is a good option if (for example) you want to process the messages for a given priority in fifo order.Alternatively, you can use a
MultiMapclass; e.g. from Apache commons collections or Guava.查看 Google Guava 库中的 TreeMultimap 类。
Check out the TreeMultimap class in the Google Guava library.
您可能完全需要另一种集合类型。但如果您打算使用 TreeMap，那么：
1) 考虑使用更复杂的 Priority 类。也许创建一种优先级类型，它既具有基本优先级 (HIGH)，又具有唯一编号，每次获得新优先级时该编号都会递增。然后使用该额外值实现 equals、hash、Comparable 等。
2) 对于每个优先级，该值可以是一个Collection。检索给定优先级的值，并将新值附加到检索到的集合的末尾。但在这一点上，使用 TreeMap 就有点大材小用了。
另外，请查看 Apache Commons Collections。
You might want another collection type altogether. But if you're intent on using TreeMap, then:
1) Consider using a more complex Priority class. Perhaps create a priority type that has both the base priority (HIGH) and a unique number that's incremented every time you get a new one. Then implement equals, hash, Comparable, etc. using that extra value.
2) For each priority, the value can be a Collection. Retrieve the value for the given priority, and append the new value on the end of the retrieved collection. At that point, though, using a TreeMap is a bit of overkill.
Also, have a look at Apache Commons Collections.
您可能想使用其他结构而不是树形图。
映射就是映射，行为就是映射，因此根据定义，在映射中不能两次使用相同的键。
You may want to use another structure rather than a treemap.
A map is a map and the behavior is what it is, so in a map you cannot have the same key twice by definition.