The best place to ask programming/development questions, imo. UPDATE: stackoverflow is the *worst* place to *ask* questions (if your first question/comment doesn't get any up-rating/response, then u can't ask anymore questions--ridiculously unrealistic), but a great reference for finding answers.

My Music (Nickleus)

20131203

Java class to test unicode and escape sequences

While reading the java language specification (java se specs, main page) (JLS) for java 7 (direct link to pdf), I came across a section on escape sequences and unicode characters (Lexical Structure, p. 15), and how they're processed by the jvm, so I made a java "main" class to test outputting unicode and escape sequences to standard out (console).

Get the code here: EscapeSequencesTest.java

I learned and noticed a couple of things while working with escape sequences:

* some unicode values found in comments cause eclipse (java?) to display an error in the java file, e.g.:

// NOTE: ('\u000C') in the comment doesn't give compile errors like examples above, e.g., '\u000D' (but without a space between "\" and "u"--otherwise eclipse gives an error)

the green value, \u000C doesn't give an error, but when eclipse reads the red value, \u000D, eclipse marks the line with a red X, with the following error msg:

Invalid character constant

so to fix this, i had to change the red value to:
\ u000D

(put a space between the backslash delimeter, \, and the unicode letter, u)

see also java.util.regex.Pattern API, for examples of escape sequences used in regular expressions, e.g.: to match characters by octal value, hexadecimal value, matching line terminators (CR, LF, CRLF), etc

No comments:

Post a Comment