java - 正则表达式和 StringTokenizer 语法错误

Question

我是正则表达式的新手StringTokenizer，并且每当我将此正则表达式放入时都会出现语法错误matches：

while ((line = br.readLine()) != null) { 
    StringTokenizer stringTokenizer = new StringTokenizer(line, "\n");

    while (stringTokenizer.hasMoreElements()) {
        String function = stringTokenizer.nextElement().toString();

        if (function.matches(\\s*(unsigned int|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;)) {
            System.out.println("VALID - ");
        }
    }
}

Answer 1

可能是复制和粘贴错误，但可能是您缺少正则表达式周围的引号以使其成为String. 例如：

while ((line = br.readLine()) != null) { 
    StringTokenizer stringTokenizer = new StringTokenizer(line, "\n");

    while (stringTokenizer.hasMoreElements()) {
        String function = stringTokenizer.nextElement().toString();

        if (function.matches("\\s*(unsigned int|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;")) {
            System.out.println("VALID - ");
        }
    }
}

Answer 2

matches方法作为方法参数......因此，将String您的正则表达式括在引号“”中 ，如下所示：

function.matches("\\s*(unsigned int|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;)")

Answer 3

用引号""将您的字符串括起来，注意当使用运算符“或” (|) 来表示两个连续的单词时，我们应该在括号中使用它们((unsigned int) | float)

while ((line = br.readLine()) != null) { 
StringTokenizer stringTokenizer = new StringTokenizer(line, "\n");

while (stringTokenizer.hasMoreElements()) {
    String function = stringTokenizer.nextElement().toString();

    if (function.matches("\\s*((unsigned int)|float|int|char|void|double)(\\s)+[a-zA-Z_](\\w)*(\\s)*\\((\\s)*((((unsigned int|float|int|char|double)(\\s)*,(\\s)*)*((unsigned int|float|int|char|double)(\\s)*))|(\\s)*|(void)(\\s)*)\\)(\\s)*\\;")) {
        System.out.println("VALID - ");
    }
}

}