Getting error The method sort(List<T>) in the type Collections is not applicable for the arguments (List<LinkedInUser>)

@Test

public void sortingTest() throws LinkedInException {

LinkedInUser Han = new LinkedInUser("Han", "hanpass");

LinkedInUser LUKE = new LinkedInUser("LUKE", "LUKEpass");

LinkedInUser leia = new LinkedInUser("leia", "leiapass");

Han.addConnection(LUKE);

Han.addConnection(leia);

List<LinkedInUser> hansConnections = Han.getConnections();


Collections.sort(hansConnections);

hansConnections.get(0).equals(leia);

hansConnections.get(1).equals(LUKE);

}

I am getting an error code with my sort, if anyone could provide insight as to how to fix this issue I would appreciate it.

The method is declared as:

public static <T extends Comparable<? super T>> void sort(List<T> list)

When you call with a List<LinkedInUser>, it means that T is a LinkedInUser, which means that LinkedInUser must implement Comparable<LinkedInUser> (or some super-type of LinkedInUser).

If you can't do that, call the overload, so you can supply a Comparator instead:

public static <T> void sort(List<T> list, Comparator<? super T> c)

Right now, without the class implementing Comparable, and without supplying a Comparator, what order did you expect the objects to be sorted in?

You need to read this documentation of Java Collections. Find the sort method and check how it works.

You can do two things:

1. Implement Comparable interface in your LinkedinUser class and override compareTo method, providing its implementation according to which you want to sort objects.

2. Use Comparator interface, and implementing the compare method(using Anonymous Interface Implementations)