RRule parser is a small java library which lets you convert a iCalendar RRule into human readable text.
RRuleParser ruleParser = new RRuleParser();
String parseResult = ruleParser.parseRRule("FREQ=MONTHLY;BYSETPOS=4;BYDAY=SU;INTERVAL=5");
// Every 5 months on fourth Sunday
Want to use another language? No problem, just implement the ILanguagePackage interface and pass it to the parser during initialization. (An example can be found here)
The default translation is in English.