Java将处理\在字符串中作为起始的转义序列。请确保您使用\，而不是（这样你得到的字符串中的实际字符\），你应该没问题。

Java will treat \ inside a string as starting an escape sequence. Make sure you use \ instead (so that you get an actual \ character in the string) and you should be ok.

快速更新：作为艾蒂安指出，如果你真的想在正则表达式本身就是一个\，你需要使用\\，因为这将产生\在字符串，这将产生\在正则表达式。

Quick Update: As Etienne points out, if you actually want a \ in the RegEx itself, you'll need to use \\, since that will produce \ in the string, which will produce \ in the RegEx.

修正后您的正则表达式：

Your regex after correction:

String regEx ="^(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.](19|20)\\d{2}$";