在 Java 正则表达式中，如何获取字符类（例如 [az]）以匹配 - 减号？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/154031/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
In a java regex, how can I get a character class e.g. [a-z] to match a - minus sign?
提问by daveb
Pattern pattern = Pattern.compile("^[a-z]+$");
String string = "abc-def";
assertTrue( pattern.matcher(string).matches() ); // obviously fails
Is it possible to have the character class match a "-" ?
是否可以让字符类匹配“-”？
回答by Tomalak
Don't put the minus sign between characters.
不要在字符之间放置减号。
"[a-z-]"
回答by albertein
Escape the minus sign
转义减号
[a-z\-]
回答by codaddict
Inside a character class [...]a -is treated specially(as a range operator) ifit's surrounded by characters on both sides. That means if you include the -at the beginning or at the end of the character class it will be treated literally(non-special).
如果字符类[...]a-被两边的字符包围，则它在内部被特殊对待（作为范围运算符）。这意味着如果您-在字符类的开头或结尾包含 ，它将按字面意思处理（非特殊）。
So you can use the regex:
所以你可以使用正则表达式：
^[a-z-]+$
or
或者
^[-a-z]+$
Since the -that we added is being treated literally there is no need to escape it. Although it's not an error if you do it.
因为-我们添加的 是按字面处理的，所以没有必要逃避它。虽然如果你这样做，这不是一个错误。
Another (less recommended) way is to not include the -in the character class:
另一种（不太推荐）的方法是不在-字符类中包含 ：
^(?:[a-z]|-)+$
Note that the parenthesis are not optional in this case as |has a very low precedence, so with the parenthesis:
请注意，在这种情况下，括号不是可选的，因为|优先级非常低，因此使用括号：
^[a-z]|-+$
Will match a lowercase alphabet at the beginning of the string and one or more -at the end.
将匹配字符串开头的小写字母和-结尾的一个或多个。
回答by John M
I'd rephrase the "don't put it between characters" a little more concretely.
我会更具体地重新表述“不要把它放在字符之间”。
Make the dash the first or last character in the character class. For example "[-a-z1-9]" matches lower-case characters, digits or dash.
使破折号成为字符类中的第一个或最后一个字符。例如“[-a-z1-9]”匹配小写字符、数字或破折号。
回答by Michael Easter
This works for me
这对我有用
Pattern p = Pattern.compile("^[a-z\-]+$");
String line = "abc-def";
Matcher matcher = p.matcher(line);
System.out.println(matcher.matches()); // true
