monline

Java *.properties files must contain only Latin-1 and/or Unicode-encoded (\udddd notation) characters. You can convert a native encoded file to this special Unicode-encoded form with the native2ascii command-line tool that is bundled with the Sun JDK. For further info take a look at this page.

Eg. if your source file is in UTF-8 encoding, then you can convert it to the proper format with the native2ascii -encoding UTF-8 source.txt something.properties command.