public void insertionSort()
    {
        int i,j;
        for(i = 0; i < employees.size(); i++)
        {
            Employee temp = employees.get(i);
            j = i - 1;
            while (j >= 0 && employees.get(j).getLastName().compareToIgnoreCase(temp.getLastName()) > 0)
            {
                employees.set(j + 1, employees.get(j));
                j--;
            }
            employees.set(j + 1, temp);
        }
        arrayDirty = false;
    }