Java 字符串数组最大最小唯一出现

Question

我的输入是 n 个字符串。我想获得唯一值，以及这些不区分大小写的字符串的出现次数。

我想到了获取数组中的输入；对其进行排序并进行循环以计算出现次数。还有别的办法吗？

Answer 1

public Map<String, Integer> calculateOccurences(Collection<String> collectionOfStrings) {
        HashMap<String, Integer> map = new HashMap<String, Integer>();
        for (String string : collectionOfStrings) {
            String stringAsLowerCase = string.toLowerCase();
            Integer integer = map.get(stringAsLowerCase);
            if (integer == null) { //this has never been added
                map.put(stringAsLowerCase, 1);
            } else {
                map.put(stringAsLowerCase, integer + 1);
            }
        }
        return map;
    }

这将 return 一个地图，其中的键是唯一的单词，每个值都会告诉您它出现了多少次。

Answer 2

您可以使用 Stream api 工具来获得您想要的内容：

List<String> list = Arrays.asList("hello","world","Hola","Mundo","hello", "world","Hola","Mundo","mundo","Hello","Hola","mundo","Mundo");

Map<String, Long> ocurrences = list
        .stream()
        .map(String::toLowerCase) // make case insensitive
        .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

System.out.println(ocurrences);

输出：

{world=2, mundo=5, hello=3, hola=3}

Java 字符串数组最大最小唯一出现

Java String Array max min unique occurrence

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arrays

string

unique

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