Why can some ASCII characters not be expressed in the form '\uXXXX' in Java source code?

Question

I stumbled over this (again) today:

class Test {
    char ok = \'\\n\';
    char okAsWell = \'\\u000B\';
    char error = \'\\u000A\';
}

It

Answer 1

It is described in 3.3. Unicode Escapes http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html. Javac first finds \uxxxx sequences in .java and replaces them with real characters then compiles. In case of

char error = '\u000A';

\u000A will be replace with newline character code (10) and the actual text will be

char error = '
';