Java - 正则表达式将第一个和最后一个字符一次性替换为另一个字符

Question

考虑我这里有这个字符串:

[Hel[don't change in the middle]lo]

如何用另一个字符替换第一个和最后一个括号，如下所示:

#Hel[don't change in the middle]lo#

我知道这是可能的:

String str = "[Hel[don't change in the middle]lo]";
str = str.replaceFirst("\\[", "#");
if (str.substring(str.length() - 1).equals("]")) {
    str = str.substring(0, str.length() - 1) + "#";
    System.out.println(str);
}

Is there any other simple way using regex, so i can replace the first and the last one in one shot?

像这样:

str = str.replace("myregex");

Answer 1

这就足够了:

System.out.println(str.replaceAll("^\\[(.*)]$", "#$1#"));