Java统计字符串中每个汉字出现的次数

可以尝试以下代码实现：

import java.util.HashMap;
import java.util.Map;

public class CountChineseCharacters {
    public static void main(String[] args) {
        String str = "Java统计字符串中每个汉字出现的次数";
        Map<Character, Integer> map = new HashMap<>();

        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if (isChinese(ch)) {
                if (map.containsKey(ch)) {
                    map.put(ch, map.get(ch) + 1);
                } else {
                    map.put(ch, 1);
                }
            }
        }

        for (Map.Entry<Character, Integer> entry : map.entrySet()) {
            System.out.println("汉字 " + entry.getKey() + " 出现了 " + entry.getValue() + " 次");
        }
    }

    public static boolean isChinese(char ch) {
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(ch);
        return ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
                || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_B
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS_SUPPLEMENT
                || ub == Character.UnicodeBlock.CJK_RADICALS_SUPPLEMENT
                || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
                || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS
                || ub == Character.UnicodeBlock.ENCLOSED_CJK_LETTERS_AND_MONTHS;
    }
}

上述代码中，使用了一个 HashMap 来记录每个汉字出现的次数，isChinese 方法用来判断字符是否为汉字，最后输出每个汉字出现的次数。