java - 无法使用正则表达式匹配字符串 "help"中的字符串 "[help]"

Question

我无法使其正确匹配。它只打印“[help]”，但我希望它匹配括号内的字符。

想要:

[help]
help

代码:

        Pattern p = Pattern.compile("\\[(\\w+)\\]");
        Matcher m = p.matcher("[help]");
        m.find();


        for (int i=0;i<m.groupCount(); i++) {
            System.out.println(m.group(i));
        }

Answer 1

您需要检查 <=对于 groupCount。像这样:

for (int i = 0; i <= m.groupCount(); i++) {

来自Matcher Javadoc :

Any non-negative integer smaller than or equal to the value returned by this method is guaranteed to be a valid group index for this matcher.