如何避免将项目放入Java HashMap时重新排序 [英] How to avoid items being re-ordered when put into java HashMap

问题描述

我正在创建一个新的Map并将字符串插入（没什么大不了的） - 但我注意到随着地图的增长，字符串被重新排序。是否有可能停止发生这种重新排序，使地图中的项目保留了订单？

 地图<字符串，字符串> x = new HashMap< String，String>（）; 
 x.put（a，b）; 
 x.put（a，c）; 
 x.put（a，d）; 
 
 x.put（1，2）; 
 x.put（1，3）; 
 x.put（1，4）; 
 
 //这显示他们不按顺序... 
（Map.Entry< String，String>条目：x.entrySet（））{
 System.out .println（IN THIS ORDER ...+ entry.getValue（））; 
 
  

解决方案

您可以使用 SortedMap 。实现接口的实际类（至少对于大多数情况）是 TreeMap的 。或者， LinkedHashMap 也保持其顺序，同时仍然使用基于散列表的容器。

I'm creating a new Map and pushing strings into it (no big deal) -but I've noticed that the strings are being re-ordered as the map grows. Is it possible to stop this re-ordering that occurs so the items in the map retain the order the were put in with?

Map<String,String> x = new HashMap<String, String>();
x.put("a","b");
x.put("a","c");
x.put("a","d");

x.put("1","2");
x.put("1","3");
x.put("1","4");

//this shows them out of order sadly...
for (Map.Entry<String, String> entry : x.entrySet()) {
    System.out.println("IN THIS ORDER ... " + entry.getValue());
}

解决方案

If you care about order, you can use a SortedMap. The actual class which implements the interface (at least for most scenarios) is a TreeMap. Alternatively, LinkedHashMap also maintains its order, while still utilizing a hashtable-based container.

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