How to append a newline to StringBuilder
It should be
r.append("\n");But I recommend you to do as below,
r.append(System.getProperty("line.separator"));System.getProperty("line.separator") gives you system-dependent newline in java. Also from Java 7 there's a method that returns the value directly: System.lineSeparator()
Another option is to use Apache Commons StrBuilder, which has the functionality that's lacking in StringBuilder.
As of version 3.6 StrBuilder has been deprecated in favour of TextStringBuilder which has the same functionality
Escape should be done with \, not /.
So r.append('\n'); or r.append("\n"); will work (StringBuilder has overloaded methods for char and String type).