How do the Arrays and Collections classes sort elements?

"As with searching, the Arrays and Collections classes provide parameterized sorting methods to sort arrays and Lists. In Java 6 and prior, the implementation was a hybrid merge/insertion sort. Java 7 switched the implementation to Tim Sort. Here too, there are several variations that rely on the natural ordering or allow you to sort a subpart of the collection. The Arrays class provides the following method, which sorts arrays of a particular type with a Comparator for that type: public static <T> void sort(T[] a, Comparator<T> c). Likewise, Collections provides the following method: public static <T> void sort(List<T> list, Comparator<T> c). Several examples of the usage of these methods are presented in Code Sample"