public void sortAlpha()
    {  
        if (a.length <= 1) return;
        String[] first = new String[a.length / 2];
        String[] second = new String[a.length - first.length];
        // Copy the first half of a into first, the second half into second
        for (int i = 0; i < first.length; i++) { first[i] = a[i]; }
        for (int i = 0; i < second.length; i++) 
        { 
            second[i] = a[first.length + i]; 
        }
        MergeSorter firstSorter = new MergeSorter(first);
        MergeSorter secondSorter = new MergeSorter(second);
        firstSorter.sortAlpha();
        secondSorter.sortAlpha();
        mergeAlpha(first, second);
    }