java 这个正则表达式有什么问题？
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What's wrong with this Regular Expression?
提问by Moshe
In java, I'm trying to detect strings of the form: optional underline, capital letters, and then curly brackets encasing two parameters. I.e. things like MAX{1,2}FUNC{3,7}_POW{9,10}
在 java 中，我试图检测以下形式的字符串：可选的下划线、大写字母，然后是包含两个参数的大括号。即像这样的东西MAX{1,2}FUNC{3,7}_POW{9,10}
I've decided to put off dealing with the parameters until later, so the regex I'm using is:
我决定推迟处理参数，所以我使用的正则表达式是：
_?[A-Z]+//{.*//}
But I'm getting the following error when trying to compile it into a Pattern object:
但是在尝试将其编译为 Pattern 对象时出现以下错误：
Exception in thread "main" java.util.regex.PatternSyntaxException: Illegal repetition near index 9
_?[A-Z]+//{.*//}
^
Anyone know what the problem is?
有谁知道问题是什么？
回答by John Zwinck
You need to escape the curly brackets in your expression, else they are treated as a repetition operator. I think you'd want to use \for this instead of //.
您需要对表达式中的大括号进行转义，否则它们将被视为重复运算符。我想你会想用\这个而不是//.
回答by ridgerunner
John is correct. But you also don't want to use the '.*'greedy-dot-star. Here is a better regex:
约翰是对的。但是您也不想使用'.*'贪心点星。这是一个更好的正则表达式：
Pattern regex = Pattern.compile("_?[A-Z]+\{[^}]+\}");
Note that you do NOT need to escape the curly brace inside a character class. This is fundamental syntax which you need to learn if you want to use regex effectively. See: regular-expressions.info- (an hour spent here will pay for itself manytimes over!)
请注意，您不需要对字符类中的花括号进行转义。如果您想有效地使用正则表达式，这是您需要学习的基本语法。请参阅：regular-expressions.info- （在这里度过了一个小时将支付本身许多在次！）
