Comments on: Convert ArrayList to Arrays in Java

By: ram

ram — Tue, 04 Oct 2011 15:07:30 +0000

thanks

By: Ahmad

Ahmad — Fri, 03 Dec 2010 16:49:44 +0000

Thank you for the great post.
Maybe, it’s too late to say this but anyway, let’s try.
About the Array to ArrayList conversion, I got error. It cannot recognize the Arrays type.
Obviously, I imported the needed classes but even the NetBeans auto-complete couldn’t help to find the reason of the error!
By a little bit searching, I figured out that the following code works fine:

String[] countries = {“India”, “Switzerland”, “Italy”, “France”};
ArrayList list = new ArrayList(Arrays.asList(countries));

Thanks,
Ahmad

By: cristian

cristian — Tue, 20 Jul 2010 00:23:19 +0000

thanks!!!!!!

By: Frsutrated

Frsutrated — Fri, 19 Mar 2010 08:39:22 +0000

If your code works then can you please explain this?

Test.java:8: generic array creation
T [] countries = list.toArray(new T[list.size()]);
^
1 error

By: Hauke

Hauke — Sat, 04 Jul 2009 15:24:44 +0000

If you use an array with the correct size within the toArray method, the result is returned within the provided array. If you use a “new T[0]” another array has to be created, that is thrown away after the type information is read.
So it is bad style to use “new T[0]“.

By: Dave

Dave — Fri, 03 Jul 2009 11:56:59 +0000

Thanks!
It was useful for me!

By: Moe Lavigne

Moe Lavigne — Fri, 03 Jul 2009 03:17:15 +0000

Maybe the following comment would have been better:

This is also works: T[] countries = list.toArray(new T[0]);

The \"toArray\" method automatically adjusts the size of the target array, but it must be initialized… I just use zero;

By: TinhTruong

TinhTruong — Fri, 03 Jul 2009 02:29:48 +0000

You don’t have to put the list.size() to the new array, just 0 is enough because it just uses the information about the type of the return array, not the size, so the following code will work:
T [] countries = list.toArray(new T[0]);

By: Moe Lavigne

Moe Lavigne — Fri, 03 Jul 2009 00:47:26 +0000

String[] countries = new String[0];

List list = new ArrayList();
list.add(“India”);
list.add(“Switzerland”);
list.add(“Italy”);
list.add(“France”);

countries = list.toArray(countries);