java的范型约束

 public static <T extends Comparable<? super T>> void sort(List<T> list) {

	Object[] a = list.toArray();

	Arrays.sort(a);

	ListIterator<T> i = list.listIterator();

	for (int j=0; j<a.length; j++) {

	    i.next();

	    i.set((T)a[j]);

	}

    }

　　

From: JDK Collections.sort方法