public class ArrayOps {

	/**
	 * @requires A.length >= 1
	 * @param A
	 *            a non-empty array of some type
	 * @return the middle element of the array
	 */
	static <T> T midpoint(T[] A) {
		assert A.length >= 1;
		return A[A.length / 2];
	}

	<T> int nonNullLength(T[] A) {
		int count = 0;
		for (T t : A) {
			if (t != null) {
				count++;
			}
		}
		return count;
	}

	public static void main(String[] args) {
		assert args.length > 0 : "Command line arguments are required";

		String result;
		result = ArrayOps.midpoint(args);
		result = ArrayOps.<String> midpoint(args);

		int count;
		ArrayOps arrayWorker = new ArrayOps();
		count = arrayWorker.nonNullLength(args);
		count = arrayWorker.<String> nonNullLength(args);

		// compile-time errors
		// result = <String>midpoint(args); //syntax error
		// result = ArrayOps.<Integer>midpoint(args); //type mismatch
		// count = <String>nonNullLength(args); //syntax error
		// count - arrayWorker.<Integer>nonNullLength(args); //type mismatch

		System.out.println(result + " " + count);
	}
}