Sorting submissions

Suppose we have a collection of submissions. We want to sort the submissions according to their “natural ordering”.

Natural ordering, here, means the default ordering of objects of a specific type when they are sorted in an array or a collection.

For example, the natural ordering of String objects is alphabetic order. The natural ordering of Date objects is chronological order.

Java allows you to define the natural ordering of objects of a specific type by implementing Comparable interface.

A class that implements the Comparable interface is said to have natural ordering. And, the compareTo() method is called the natural comparison method.

So the natural ordering of Submission is based on the order they were received, as it is defined in the Submission.compareTo method.

If we instantiate several objects of type Submission and store them in a Java Collection such as a List, then we can use Collections.sort to order (sort) the submissions based on their natural ordering.

An example is provided in the in the demo package of the starter code.

List<String> students = getStudents();
List<Submission> submissions = getSubmissions(students);

System.out.print("Submission sorted (natural ordering):");