In Java, there are many ways to maintain a Collection with elements

in sorted order.

Some collections like TreeSet store elements in the natural

ordering. In case of natural ordering we have to implement

Comparable interface for comparing the elements.

We can also maintain custom ordering by providing a custom

Comparator to a Collection.

Another option is to use the utility method Collections.sort() to sort

a List. This sorting gives nlog(n) order of performance. But if we

have to use this method multiple times then it will be costly on

performance.

Another option is to use a PriorityQueue that provides an ordered

queue. The main difference between PriorityQueue and

Collections.sort() is that PriorityQueue maintains a queue in Order

all the time, but we can only retrieve head element from queue. We

cannot access the elements of PriorityQueue in Random order.

We can use TreeSet to maintain sorted order of elements in

collection if there are no duplicate elements in collection.

https://www.javatpoint.com/Sorting-in-collection-framework