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javaapache-commonsapache-commons-lang

How can I include the caret character ^ in an Apache Commons CharSet?

The Apache Commons CharSet class has its own syntax for characters to be included in the set. In that syntax the caret character (^) has special meaning (negation) but there isn't any documentation about how to include the caret in the set itself without negating characters that come after it. For example, the following unexpectedly returns false:

CharSet.getInstance("!@#$%^&").contains('&');

Interestingly, the following returns true, which I think is a bug (although the JavaDoc doesn't specify how it should behave):

CharSet.getInstance("!@#$%^&").contains('^')

Update: see comment by @Duncan below for explanation of this behavior)

My question is, how can I specify a CharSet that includes ^ as a character without affecting other characters in the set?

Solution

  • The getInstance method looks like this:

     public static CharSet getInstance(String... setStrs)

    According to the javadoc it is completely valid (and it is kind of documented) to do this:

    CharSet.getInstance("^", "!@#$%&").contains('^')