src/share/classes/java/util/Collections.java

*** 150,159 ****
--- 150,162 ----
       *         detects that the natural ordering of the list elements is
       *         found to violate the {@link Comparable} contract
       */
      public static <T extends Comparable<? super T>> void sort(List<T> list) {
          Object[] a = list.toArray();
+         if(a.length <= 1) {
+             return;
+         }
          Arrays.sort(a);
          ListIterator<T> i = list.listIterator();
          for (int j=0; j<a.length; j++) {
              i.next();
              i.set((T)a[j]);
*** 212,226 ****
       * @throws IllegalArgumentException (optional) if the comparator is
       *         found to violate the {@link Comparator} contract
       */
      public static <T> void sort(List<T> list, Comparator<? super T> c) {
          Object[] a = list.toArray();
          Arrays.sort(a, (Comparator)c);
!         ListIterator i = list.listIterator();
          for (int j=0; j<a.length; j++) {
              i.next();
!             i.set(a[j]);
          }
      }
  
  
      /**
--- 215,232 ----
       * @throws IllegalArgumentException (optional) if the comparator is
       *         found to violate the {@link Comparator} contract
       */
      public static <T> void sort(List<T> list, Comparator<? super T> c) {
          Object[] a = list.toArray();
+         if(a.length <= 1) {
+             return;
+         }
          Arrays.sort(a, (Comparator)c);
!         ListIterator<T> i = list.listIterator();
          for (int j=0; j<a.length; j++) {
              i.next();
!             i.set((T) a[j]);
          }
      }
  
  
      /**