How to properly trim whitespaces from a string in Java?

Question

The JDK's String.trim() method is pretty naive, and only removes ascii control characters.

Apache Commons' StringUtils.strip() is slightly better, but uses the JDK's Character.isWhitespace(), which doesn't recognize non-breaking space as whitespace.

So what would be the most complete, Unicode-compatible, safe and proper way to trim a string in Java?

And incidentally, is there a better library than commons-lang that I should be using for this sort of stuff?

Answer 1

Google has made guava-libraries available recently. It may have what you are looking for:

CharMatcher.inRange('', ' ').trimFrom(str)

is equivalent to String.trim(), but you can customize what to trim, refer to the JavaDoc.

For instance, it has its own definition of WHITESPACE which differs from the JDK and is defined according to the latest Unicode standard, so what you need can be written as:

CharMatcher.WHITESPACE.trimFrom(str)