在 HashMap 中找到最接近的答案 [英] Find The Closest Answer in HashMap

问题描述

我想在 hashmap 中搜索一个键并找到离该键最近的一个！

I want to search for a key in a hashmap and find the nearest one to that key!

    HashMap<Long, Object> map = new HashMap<Long , Object>();

所以基本上我想搜索一个 long，如果它在地图中不存在，则找到与该 long 值最接近的匹配！我该怎么做！?

so basically I want to search for a long and if it didn't exist in the map find the nearest match to that long value! How can I do that!?

提前感谢

推荐答案

你不能用 HashMap 来完成它而不迭代它的所有键.我认为这不是您所追求的，所以这是一种使用 TreeMap 的方法:

You cannot do it with HashMap without iterating over all of its keys. I assume that this is not what you are after, so here is a way do it with a TreeMap:

TreeMap<Long,Object> map = new TreeMap<Long,Object>();
Long key = 42;
Map.Entry<Long,Object> low = map.floorEntry(key);
Map.Entry<Long,Object> high = map.ceilingEntry(key);
Object res = null;
if (low != null && high != null) {
    res = Math.abs(key-low.getKey()) < Math.abs(key-high.getKey())
    ?   low.getValue()
    :   high.getValue();
} else if (low != null || high != null) {
    res = low != null ? low.getValue() : high.getValue();
}

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