正则表达式和 StringTokenizer 语法错误

Question

我是正则表达式和

StringTokenizer

的新手，每当我将此正则表达式放入

matches

中时，我都会收到语法错误：

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

用引号将字符串括起来 " "，请注意，当使用运算符“或”(|) 表示两个连续单词时，我们应该将它们放在括号中

((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 - ");
    }
}

}

Answer 2

可能是复制和粘贴错误，但也可能是您缺少正则表达式周围的引号，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 3

matches

方法 采用

String

作为方法参数...因此，请用引号将正则表达式括起来 " " 像这样：

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)*\\;)")