如何在HashMap中保留插入顺序？ [重复]

本文翻译自：How to preserve insertion order in HashMap? [duplicate]

This question already has an answer here: 这个问题在这里已有答案：

• Java Class that implements Map and keeps insertion order? 实现Map并保持插入顺序的Java类？ 8 answers 8个答案

I'm using a HashMap . 我正在使用HashMap 。 When I iterate over the map, the data is returned in (often the same) random order. 当我遍历地图时，数据以（通常是相同的）随机顺序返回。 But the data was inserted in a specific order, and I need to preserve the insertion order. 但是数据是按特定顺序插入的，我需要保留插入顺序。 How can I do this? 我怎样才能做到这一点？

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#1楼

参考：https://stackoom.com/question/iwD3/如何在HashMap中保留插入顺序-重复

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#2楼

LinkedHashMap is precisely what you're looking for. LinkedHashMap正是您所需要的。

It is exactly like HashMap , except that when you iterate over it, it presents the items in the insertion order. 它与HashMap完全相同，只是当您迭代它时，它会以插入顺序显示项目。

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#3楼

HashMap is unordered per the second line of the documentation: 根据文档的第二行， HashMap是无序的：

This class makes no guarantees as to the order of the map; 这个类不保证地图的顺序; in particular, it does not guarantee that the order will remain constant over time. 特别是，它不保证订单会随着时间的推移保持不变。

Perhaps you can do as aix suggests and use a LinkedHashMap , or another ordered collection. 也许你可以像aix建议的那样使用LinkedHashMap或其他有序集合。 This link can help you find the most appropriate collection to use. 此链接可以帮助您找到最合适的集合。