Need some help with this java problem

Implement the following generic Java method using an O(n2) sort and a comparator: public static void aSort(E[] list, Comparator comparator). Write test program that creates a list of at least 5 elements of the class type created in problem 3 above, calls the above method to sort the list, then outputs the sorted list via calls to toString.

Problem 3 Question which I have also been having trouble implementing

Create a Java class named Circle that implements java.io.Serializable interface (for more information see: https://docs.oracle.com/javase/7/docs/api/java/io/Serializable.html) and models a circle based on radius. Radius cannot be less than zero. Implement the getter and setter method for radius. Also include an overriding of toString in the circle class. Create the class' comparator which compares two objects of type Circle.