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 ...