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Java 判斷字符是中文還是英文標點符號的方法

編輯：程式設計綜合問答

在 Java 中判斷字符屬於中文標點還是英文標點，核心原理是利用字符編碼範圍：中文字符（含標點）通常佔用 2-4 字節 (UTF-16 char 無法直接判斷)，需通過 Unicode 碼點範圍或字節長度區分。

核心原理

英文字符 (ASCII)：Unicode 碼點 0x0000-0x007F，UTF-8 編碼 1 字節
中文字符 (CJK 統一表意文字)：Unicode 碼點 0x4E00-0x9FFF，UTF-8 編碼 3 字節
中文標點：Unicode 碼點主要在 0x3000-0x303F (CJK 符號和標點)、0xFF00-0xFFEF (半形及全形形式)
英文標點：Unicode 碼點在 ASCII 範圍內 (如 0x21 !, 0x2C ,, 0x2E ., 0x3F ? 等)

實用判斷方法

方法一：Unicode 碼點範圍判斷 (最準確)


public static boolean isChinesePunctuation(char c) {
    int codePoint = (int) c;
    // CJK 符號和標點區塊: 3000-303F
    // 半形及全形形式區塊: FF00-FFEF (含全形英文標點)
    return (codePoint >= 0x3000 && codePoint <= 0x303F) ||
           (codePoint >= 0xFF00 && codePoint <= 0xFFEF);
}

public static boolean isEnglishPunctuation(char c) {
    int codePoint = (int) c;
    // ASCII 標點範圍 (非字母數字)
    return (codePoint >= 0x21 && codePoint <= 0x2F) ||  // !"#$%&'()*+,-./
           (codePoint >= 0x3A && codePoint <= 0x40) ||  // :;<=>?@
           (codePoint >= 0x5B && codePoint <= 0x60) ||  // [\]^_`
           (codePoint >= 0x7B && codePoint <= 0x7E);    // {|}~
}

方法二：Character 類別方法 (Java 7+)


public static boolean isChineseChar(int codePoint) {
    // 判斷是否為 CJK 統一表意文字
    return Character.UnicodeBlock.of(codePoint) == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS;
}

public static boolean isPunctuation(int codePoint) {
    return Character.getType(codePoint) == Character.START_PUNCTUATION ||
           Character.getType(codePoint) == Character.END_PUNCTUATION ||
           Character.getType(codePoint) == Character.CONNECTOR_PUNCTUATION ||
           Character.getType(codePoint) == Character.DASH_PUNCTUATION ||
           Character.getType(codePoint) == Character.OTHER_PUNCTUATION;
}

// 組合判斷
public static boolean isChinesePunctuation(int codePoint) {
    return isPunctuation(codePoint) && 
           (Character.UnicodeBlock.of(codePoint) == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION ||
            Character.UnicodeBlock.of(codePoint) == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS);
}

方法三：字節長度判斷 (簡易，僅適用 UTF-8 編碼環境)


// 注意：Java char 是 UTF-16 代碼單元，補充字符需用 codePoint
public static boolean isLikelyChinese(char c) {
    // 簡易判斷：非 ASCII 視為中文 (含標點)
    return c > 0x7F; // ASCII 範圍 0-127
}

// 更準確：獲取 UTF-8 字節長度
public static int utf8ByteLength(String str) {
    return str.getBytes(StandardCharsets.UTF_8).length;
}
// 中文字符通常 3 字節，英文 1 字節

完整統計示例


public static void countCharTypes(String str) {
    int chineseCount = 0, englishCount = 0, chinesePunct = 0, englishPunct = 0, other = 0;
    
    for (int i = 0; i < str.length(); ) {
        int codePoint = str.codePointAt(i);
        i += Character.charCount(codePoint); // 處理補充字符
        
        if (Character.isLetter(codePoint)) {
            if (isChineseChar(codePoint)) chineseCount++;
            else englishCount++;
        } else if (isChinesePunctuation(codePoint)) {
            chinesePunct++;
        } else if (isEnglishPunctuation((char)codePoint)) {
            englishPunct++;
        } else {
            other++;
        }
    }
    System.out.printf("中文字:%d 英文字:%d 中標:%d 英標:%d 其他:%d%n", 
        chineseCount, englishCount, chinesePunct, englishPunct, other);
}