字图计数器

Question

如何在单词上使用 split(" ") 实例化地图，并遍历生成的数组。 * 在生成的 for 循环中，每次遇到映射中还不是键的词时，都应向映射插入一个新键，每次遇到映射中已存在的词时，都应将其添加到词的计数值中地图。

Map<String, Integer> map = new Hash Map<String, Integer>();
    for (String s : string Array) {
        if (containerization(s)) {
            map.put(s, map.get(s) + 1);
        } else {
            map.put(s, 1);
        }
    }

  
    return map;

}

}

Answer 1

您可能要根据描述编写的代码：

class Main {
    public static void main(String[] args) {
        String input = "Hello world Hello all";
        Map<String, Integer> wordMap = countWords(input);
        System.out.println(wordMap); // {all=1, world=1, Hello=2}
    }

    private static HashMap<String, Integer> countWords(final String text) {
        HashMap<String, Integer> wordMap = new HashMap<>();
        String[] words = text.split(" "); // split the input string by space
        for (String word : words) {
            if (wordMap.containsKey(word)) {
                wordMap.put(word, wordMap.get(word) + 1); // increment count of existing word
            } else {
                wordMap.put(word, 1); // add new word to the map
            }
        }
        return wordMap;
    }
}

---

注意可以这样改进：

class Main {
    public static void main(String[] args) {
        String input = "Hello world Hello all";
        Map<String, Integer> wordMap = countWords(input);
        System.out.println(wordMap); // {all=1, world=1, Hello=2}
    }

    private static HashMap<String, Integer> countWords(final String text) {
        HashMap<String, Integer> wordMap = new HashMap<>();
        String[] words = text.split(" "); // split the input string by space
        for (String word : words) {
            wordMap.merge(word, 1, Integer::sum);
        }
        return wordMap;
    }
}

或者那样：

class Main {
    public static void main(String[] args) {
        String input = "Hello world Hello all";
        Map<String, Integer> wordMap = countWords(input);
        System.out.println(wordMap); // {all=1, world=1, Hello=2}
    }

    private static Map<String, Integer> countWords(final String text) {
        return Arrays.stream(text.split(" "))
            .collect(groupingBy(identity(), summingInt(x -> 1)));
    }
}

Answer 2

还有一种方法。使用Map.merge.

Map<String, Integer> map = new HashMap<String, Integer>();
String s = "one three    five four   four"
        + "            two three five     four  four"
        + "   five five  three    two five";

\\s+

- 在一个或多个空白字符处拆分

for (String word : s.split("\\s+")) {
    map.merge(word, 1, Integer::sum);
}

map.entrySet().forEach(System.out::println);

版画

four=4
one=1
two=2
five=5
three=3