The Collections.sort() method is a static method that belongs to the java.util.Collections class. It is used to sort the elements of a list or a collection in a specified order. The order can be either ascending or descending, or based on a custom comparator¹.

The Collections.sort() method has two overloaded forms:

• public static <T extends Comparable<? super T>> void sort(List<T> list): This method sorts the elements of the list in their natural order, which is defined by the compareTo() method of the Comparable interface that the elements implement¹. If the elements do not implement Comparable, or if the list contains elements that are not mutually comparable, this method will throw a ClassCastException³.

• public static <T> void sort(List<T> list, Comparator<? super T> c): This method sorts the elements of the list according to the order induced by the specified comparator, which is an object that implements the Comparator interface and defines a custom way of comparing two elements¹. If the comparator is null, this method will use the natural order of the elements³.

Here are some examples of using the Collections.sort() method: