ArrayTest.java

import static java.lang.System.currentTimeMillis;

import java.util.ArrayList;

public class ArrayTest
{
	public static void main(String[] args)
	{
		int numOfIt = 10;

		int size = 10_000_000;

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			int[] arr = new int[size];
			for (int i = 0; i < arr.length; i++)
			{
				arr[i] = i;
			}

			for (int i = 0; i < arr.length; i++)
			{
				arr[i] = i + 1;
			}

			long end = currentTimeMillis();
			print("Arr", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			int[] arr = new int[size];
			for (int i = 0; i < size; i++)
			{
				arr[i] = i;
			}

			for (int i = 0; i < arr.length; i++)
			{
				arr[i] = i + 1;
			}

			long end = currentTimeMillis();
			print("Arr-int", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>();
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			for (int i = 0; i < l.size(); i++)
			{
				l.set(i, l.get(i) + 1);
			}

			long end = currentTimeMillis();
			print("List-wo/size-for-set-", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			for (int i = 0; i < l.size(); i++)
			{
				l.set(i, l.get(i) + 1);
			}

			long end = currentTimeMillis();
			print("List-for-set", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			int a = 0;
			for (int i = 0; i < l.size(); i++)
			{
				a = l.get(i) + 1;
			}

			long end = currentTimeMillis();
			print("List-for", it, end - start, a); // the line maybe ignored if a is
																							// never used
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			int a = 0;
			for (int i : l)
			{
				a = i + 1;
			}

			long end = currentTimeMillis();
			print("List-it", it, end - start, a);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			int[] arr = new int[size];
			for (int i = 0; i < arr.length; i++)
			{
				arr[i] = i;
			}

			int[] arr2 = new int[size];
			for (int i = 0; i < arr2.length; i++)
			{
				arr2[i] = i + 1;
			}

			long end = currentTimeMillis();
			print("Arr-copy", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			ArrayList<Integer> l2 = new ArrayList<>(size);
			for (int i = 0; i < l.size(); i++)
			{
				l2.add(l.get(i) + 1);
			}

			long end = currentTimeMillis();
			print("List-copy-for", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			ArrayList<Integer> l2 = new ArrayList<>(size);
			for (int i : l)
			{
				l2.add(i + 1);
			}

			long end = currentTimeMillis();
			print("List-copy-it", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
			{
				l.add(i);
			}

			ArrayList<Integer> l2 = new ArrayList<>(l);
			// for (int i = 0; i < l.size(); i++)
			// {
			// l2.add(l.get(i) + 1);
			// }

			long end = currentTimeMillis();
			print("List-copy-internal", it, end - start);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			int[] arr = null;
			for (int n = 0; n < size; n++)
			{
				arr = new int[10];
				for (int i = 0; i < arr.length; i++)
				{
					arr[i] = i;
				}
			}

			long end = currentTimeMillis();
			print("Arr-multiple", it, end - start, arr);
		}

		for (int it = 0; it < numOfIt; it++)
		{
			long start = currentTimeMillis();

			ArrayList<Integer> l = null;
			for (int n = 0; n < size; n++)
			{
				l = new ArrayList<>(10);
				for (int i = 0; i < 10; i++)
				{
					l.add(i);
				}
			}

			long end = currentTimeMillis();
			print("List-multiple", it, end - start, l);
		}
	}

	// The last parameter is for convenience. If a local variable is not used,
	// some Java compilers ignore the line. That would distort the tests.
	private static void print(final String name, int it, final long time,
			Object... var)
	{
		System.out.printf(name + "-%d time:%d\n", it, time);
	}
}