Arrays and Collections Classes

Question:
Time Complexity of Arrays.sort() and Collections.sort() "STATIC" methods
NOTE: Arrays and Collections (BOTH with s) are classes in Java

Arrays is class in util package,
Collections is class of util package,
Collection is interface of util package

VERY VERY IMP NOTE: PLURAL (i.e. Arrays and Collections) are CLASSES
whereas SINGULAR form (e.g. Collection) is INTERFACE


IMP NOTE: There is no such thing as "Array" in Java. "Arrays" exist BUT "Array" does NOT exist.
Arrays - Class (http://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html)
Collection - INTERFACE (http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html)
Collections - Class (http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html)

Source: http://stackoverflow.com/questions/4254122/what-is-the-time-complexity-of-this-sort-method?rq=1
Solution: The time complexity of this predefined method of Arrays class and Collections class is nlgn