An enumeration of common separators that are used for JDOM output.
These enumerated values can be used as input to the
Format#setLineSeparator(LineSeparator) method. Additionally, the
names of these constants can be also be used in the System Property
JDOMConstants#JDOM2_PROPERTY_LINE_SEPARATOR which is used to
define the default Line Separator sequence for JDOM output. See
#DEFAULT Javadoc.
JDOM has historically used the CR/NL sequence '\r\n' as a line-terminator.
This sequence has the advantage that the output is easily opened in the
'Notepad' editor on Windows. Other editors on other platforms are typically
smart enough to automatically adjust to whatever termination sequence is
used in the document. The XML specification requires that the CR/NL sequence
should be 'normalized' to a single newline '\n' when the document is parsed
(XML 1.1 End-Of-Line
Handling). As a result there is no XML issue with the JDOM default CR/NL
end-of-line sequence.
It should be noted that because JDOM internally stores just a '\n' as a line
separator that any other output separator requires additional processing to
output. There is a distinct performance benefit for using the UNIX, or NL
LineSeparator for output.
JDOM has always allowed the line-terminating sequence to be customised (or
even disabled) for each
XMLOutputter operation by using this Format
class.
JDOM2 introduces two new features in relation to the end-of-line sequence.
Firstly, it introduces this new
LineSeparator enumeration which
formalises the common line separators that can be used. In addition to the
simple String-based
Format#setLineSeparator(String) method you can
now also call
Format#setLineSeparator(LineSeparator) with one of the
common enumerations.
The second new JDOM2 feature is the ability to set a global default
end-of-line sequence. JDOM 1.x forced the default sequence to be the CRLF
sequence, but JDOM2 allows you to set the system property
JDOMConstants#JDOM2_PROPERTY_LINE_SEPARATOR which will be used as the
default sequence for Format. You can set the property to be the name of one
of these LineSeparator enumerations too. For example, the following will
cause all default Format instances to use the System-dependent end-of-line
sequence instead of always CRLF:
java -Dorg.jdom2.output.LineSeparator=SYSTEM ...