Performance comparison between LinkedList vs. ArrayDeque

Java doc mentions that when used as a queue, ArrayDeque is faster than LinkedList. So I did an experiment and the code looks simply like below:

import java.util.*;

public class ListPerfTest {

private static final Queue List = new LinkedList();

private static final Queue Queue2 = new ArrayDeque();

private static int Count = 1000000;

public static void main(String ... args) {

if (args.length > 1) {
Count = Integer.parseInt(args[0]);
}
System.out.println("Test starts");
long start = System.nanoTime();
for (int i = 0; i <>
List.offer(i + "");
}
for (int i = (Count >> 1); i <>
List.peek();
List.poll();
}
long end = System.nanoTime();
System.out.println("Using linked list takes about:" + (end - start) / 1000000 + "ms");

System.gc();

start = System.nanoTime();
for (int i = 0; i <>
Queue2.offer(i + "");
}
for (int i = (Count >> 1); i <>
Queue2.peek();
Queue2.poll();
}
end = System.nanoTime();
System.out.println("Using ArrayDeque takes about:" + (end - start) / 1000000 + "ms");
System.out.println("Test finished");

}

}

So on my Dell T3500 machine (Quad Core Xero chip) and using Java server VM, the output looks like below:

Test starts
Using linked list takes about:256ms
Using ArrayDeque takes about:106ms
Test finished

We can see that the ArrayDeque is more than twice as fast as LinkedList implementation. The benefit is coming from two places as far as I understand.

1. ArrayDeque is backed by Array and Array is more cache-locality friendly than LinkedList (since it has to go through another indirection in order to get where next node is).
2. ArrayDeque is memory efficient than LinkedList since it does not have to keep an additional reference to the next node.

So using ArrayDeque instead of LinkedList when using it in a queue like fashion.