Exception in thread "main" java.lang.NullPointerException
        at java.util.Arrays.mergeSort(Arrays.java:1156)
        at java.util.Arrays.mergeSort(Arrays.java:1167)
        at java.util.Arrays.mergeSort(Arrays.java:1167)
        at java.util.Arrays.mergeSort(Arrays.java:1167)
        at java.util.Arrays.sort(Arrays.java:1080)
        at ListOfItems.<init>(ListOfItems.java:71)
        at ListOfItems.main(ListOfItems.java:80)