Java regex: why numbers [0-9], comma etc. is not an unicode?

问题

class Test
{
    public static void main (String[] args)
    {
        String regex = "\\p{L}";
        System.out.println("0".matches(regex));
    }
}

The code above prints false, but I was expecting true because isn't ASCII a subset of unicode? "0" is part of ASCII, so I think it should also belongs to a unicode letter.

Also, comma, period etc prints "false" true, while "a" will print true.

回答1:

It is because \\p{L} matches a Unicode letter and you're matching a digit.

You can use:

[\\p{L}\\p{Nd}.,]

to match a Unicode digit or letter.

You should also use (?U) in front of your regex for Unicode support like this:

String regex = "(?U)[\\p{L}\\p{Nd}.,]+";

来源：https://stackoverflow.com/questions/41846074/java-regex-why-numbers-0-9-comma-etc-is-not-an-unicode