java - 如何发现 HashMap 中哪个值出现次数最多？

Question

Map<String,String> votes = new HashMap<String,String>
votes.put("Henk","School");
votes.put("Elise","School");
votes.put("Jan","Work");
votes.put("Mert","Party");

我如何检索最常出现在上面的 HashMap 中的值，在本例中为“School”。我将不胜感激最有效和最清晰的方法。

Answer 1

一个更简单的解决方案是只查看值。

public static <E> E mostFrequentElement(Iterable<E> iterable) {
    Map<E, Integer> freqMap = new HashMap<>();
    E mostFreq = null;
    int mostFreqCount = -1;
    for (E e : iterable) {
        Integer count = freqMap.get(e);
        freqMap.put(e, count = (count == null ? 1 : count+1));
        // maintain the most frequent in a single pass.
        if (count > mostFreqCount) {
            mostFreq = e;
            mostFreqCount = count;
        }
    }
    return mostFreq;
}

对于 map 你可以做

V v = mostFrequentElement(map.values());