Java正则表达式问题

Question

使用此[0-9]+_[0-9]+_[0-9]+(_[0-9]+){0,1}正则表达式时会引发以下异常。

Caused by: java.util.regex.PatternSyntaxException: Unclosed counted closure near index 31
[0-9]+_[0-9]+_[0-9]+(_[0-9]+){0
                               ^
    at java.util.regex.Pattern.error(Pattern.java:1713)
    at java.util.regex.Pattern.closure(Pattern.java:2759)
    at java.util.regex.Pattern.group0(Pattern.java:2537)
    at java.util.regex.Pattern.sequence(Pattern.java:1806)
    at java.util.regex.Pattern.expr(Pattern.java:1752)
    at java.util.regex.Pattern.compile(Pattern.java:1460)
    at java.util.regex.Pattern.<init>(Pattern.java:1133)
    at java.util.regex.Pattern.compile(Pattern.java:823)

我是从XML文件中读到的。

Answer 1

你可能想要这个：

[0-9]+_[0-9]+_[0-9]+(_[0-9]+)?

Answer 2

你必须用反斜杠转义逗号：

[0-9]+_[0-9]+_[0-9]+(_[0-9]+){0\,1}