ArrayList insert performance java 1.5 vs. 1.6

Question

Hi,
Does anyone know what the deal is here?
import java.util.*;
public class Test
public static void main(String[] args)
insert(null);
insert(10000000);
insert(null);
insert(10000000);
insert(null);
insert(10000000);
private static void insert(Integer init)
List<Integer> list;
if (init != null)
list = new ArrayList<Integer>(init);
else
list = new ArrayList<Integer>();
System.out.println("using initial size of "+((init != null) ? init : "default"));
long now = System.currentTimeMillis();
for (int i=0; i<10000000; i++)
list.add(i);
System.out.println(System.currentTimeMillis()-now+" ms");
+ /usr/jdk/java-1.6/bin/java -cp . -server Test
using initial size of default
2536 ms
using initial size of 10000000
3346 ms
using initial size of default
2430 ms
using initial size of 10000000
1253 ms
using initial size of default
3017 ms
using initial size of 10000000
1203 ms
(and 1.5)
+ /usr/jdk/java-1.5/bin/java -cp . -server Test
using initial size of default
2575 ms
using initial size of 10000000
1613 ms
using initial size of default
3952 ms
using initial size of 10000000
1508 ms
using initial size of default
3994 ms
using initial size of 10000000
1468 ms
Once hotspot kicks in the perf advantage is huge, but why does it take so long for this to happen on 1.6? Is there anyway to tune it? Also, why does the default size slow down so much over time. Is it the GC?
thx.

Answer 1

Is Java 1.5 considered offially released (no longer
beta)?Yes.
If so, and I install it on my machine, could it break
any 1.4.2 apps?Yes - in Java 5, read about javac options -source and -target, and the Compatibility document for changes
If so, is there a way to install 1.5 and keep my
installation on 1.4.2?Yes - install in separate directories
If I do that, how do I specify
which one I want to run? That is, make the command
java MyAppName
unambiguous?Use batch or shell files to set the directories and classpath, and use the full path to the executables.
>
Thanks for any info,
John