How to sort an array of objects containing null elements?

Question

In my program an array fClasses of fixed length [7] of objects is created, each object is a class FClass that contains 3 Strings, an <

Answer 1

You have to create a Comparator, rather than use a Comparable.

public class FClassComparator implements Comparator 
{
    public int compare(FClass left, FClass right) {
        // Swap -1 and 1 here if you want nulls to move to the front.
        if (left == null) return right == null ? 0 : 1;
        if (right == null) return -1;
        // you are now guaranteed that neither left nor right are null.

        // I'm assuming avg is int. There is also Double.compare if they aren't.
        return Integer.compare(left.avg, right.avg); 
    }
}

Then call sort via:

Arrays.sort(fClassArray, new FClassComparator());