如何反向遍历链接哈希映射？ [英] How to traverse Linked Hash Map in reverse?

问题描述

可能重复：

以相反的顺序迭代LinkedHashMap

如何以相反的顺序遍历链接的哈希映射？地图中有预定义的方法吗？

How to traverse Linked Hash Map in a reverse order? Is there any predefined method in map to do that?

我按如下方式创建它：

LinkedHashMap<Integer, String> map = new LinkedHashMap<Integer,String>();
map.put(1, "one");
map.put(2, "two");
map.put(3, "three");

推荐答案

List<Entry<Integer,String>> list = new ArrayList<>(map.entries());

for( int i = list.size() -1; i >= 0 ; i --){
    Entry<Integer,String> entry = list.get(i);
}

不是很漂亮，而且代价是条目集的副本，如果您的地图有大量条目可能是个问题。

Not really pretty and at the cost of a copy of the entry set, which if your map has a significant number of entries might be a problem.

excellant Guava库有一个 [List.reverse（List<>）] [2] ，它允许你为每个使用Java 5样式循环而不是索引循环：

The excellant Guava library have a [List.reverse(List<>)][2] that would allow you to use the Java 5 for each style loop rather than the indexed loop:

//using guava
for( Entry entry : Lists.reverse(list) ){
    // much nicer
}

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