如何在 Java 中拆分 HashMap

问题描述

我想知道是否可以将 HashMap 拆分为更小的子图.

I was wondering if it is possible to split a HashMap into smaller sub-maps.

在我的例子中，我有一个 100 个元素的 HashMap，我想从原始元素创建 2 个(或更多)更小的 HashMap，第一个包含 0 到 49 的条目，第二个包含 50 到 99 的条目.

In my case I have a HashMap of 100 elements and I would like to create 2 (or more) smaller HashMaps from the original one, the first containing the Entries from 0 to 49, the second containing the Entries from 50 to 99.

Map <Integer, Integer> bigMap = new HashMap <Integer, Integer>();

//should contains entries from 0 to 49 of 'bigMap'
Map <Integer, Integer> smallMap1 = new HashMap <Integer, Integer>(); 


//should contains entries from 50 to 99 of 'bigMap'
Map <Integer, Integer> smallMap2 = new HashMap <Integer, Integer>();

有什么建议吗?非常感谢！

Any suggestions? Many thanks!

推荐答案

一定要用HashMap吗?

TreeMap 非常适合这种事情.这是一个示例(注意 0、50 和 99 是映射键，不是索引):

TreeMap is really good for this kind of things. Here's an example (note that 0, 50, and 99 are map keys, not indices):

TreeMap<Integer, Integer> sorted = new TreeMap<Integer, Integer>(bigMap);

SortedMap<Integer, Integer> zeroToFortyNine = sorted.subMap(0, 50); // toKey inclusive, fromKey exclusive
SortedMap<Integer, Integer> fiftyToNinetyNine = sorted.subMap(50, true, 99, true);

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