.properties

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Properties
File extension:	.properties
Type of format:	ASCII

.properties is a file extension for files mainly used in Java related technologies to store the configurable parameters of an application.

.properties files can use the number sign (#) or the exclamation mark (!) to denote that all text following it is a comment. The backwards slash is used to escape a character. An example of a properties file is provided below.

# You are reading the ".properties" entry in the English wikipedia.
! The exclamation mark can also mark text as comments.
website = http://en.wikipedia.org
language = English
# The backslash below tells the application to continue reading
# the value onto the next line.
message = Welcome to \
          Wikipedia!
# Add spaces to the key
key\ with\ spaces = This is the value that could be looked up with the key "key with spaces".

A .properties file maps a key with a value and is essentially a hash table. In the example above, "website" would be a key, and its corresponding value would be "http://en.wikipedia.org". While the number sign and the exclamation mark marks text as comments, it has no effect when it is part of a property. Thus, the key "message" has the value "Welcome to Wikipedia!" and not "Welcome to Wikipedia". Note also that all of the whitespace in front of "Wikipedia!" is excluded completely.

[edit] See also

• java.io.Properties.load(java.io.InputStream) - gives the precise semantics of well-formed Java property files