Array vs List iteration throughput test

ArrayVsListThroughputTests.java

public class ArrayVsListThroughputTests {

	static long TIMEOUT = 5000;

	@Test
	public void testArrayVsListIteration() {
		int items = 10;
		String[] strArray = new String[items];
		List<String> strList = new ArrayList<String>();
		for(int i = 0; i < items; i++) {
			strArray[i] = "Hello World!";
			strList.add("Hello World!");
		}

		doIterationTest("list", strList);
		doIterationTest("array", strArray);
		doArrayIterationTest(strArray);
	}

	private void doIterationTest(String type, Object obj) {
		boolean isArray = obj.getClass().isArray();

		long start = System.currentTimeMillis();
		while(System.currentTimeMillis() - start < TIMEOUT) {
			if(isArray) {
				for(Object o : (Object[])obj) {
					counter.incrementAndGet();
				}
			} else {
				for(Object o : (Iterable<?>)obj) {
					counter.incrementAndGet();
				}
			}
		}
		long end = System.currentTimeMillis();
		double elapsed = end - start;

		System.out.format("%s iterator throughput %s/sec in %sms%n",
		                  type,
		                  (counter.get() / (int)(elapsed / 1000)),
		                  (int)elapsed);
	}

	private void doArrayIterationTest(Object[] array) {
		Map<Long, Object[]> arrayCache = new HashMap<Long, Object[]>();
		long threadId = (int)Thread.currentThread().getId();
		int len = array.length;

		Object[] newArray = new Object[len];
		System.arraycopy(array, 0, newArray, 0, len);
		arrayCache.put(threadId, newArray);

		long start = System.currentTimeMillis();
		while(System.currentTimeMillis() - start < TIMEOUT) {
			Object[] objs = arrayCache.get(threadId);
			for(int i = 0; i < len; i++) {
				Object o = objs[i];
				counter.incrementAndGet();
			}
		}
		long end = System.currentTimeMillis();
		double elapsed = end - start;

		System.out.format("array for throughput %s/sec in %sms%n",
		                  (counter.get() / (int)(elapsed / 1000)),
		                  (int)elapsed);
	}

}