Re: Adding arrays to arrays...

From:

Mark Space <markspace@sbc.global.net>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 20 Aug 2008 18:12:11 -0700

Message-ID:

<Jg3rk.4737$zv7.2714@flpi143.ffdc.sbc.com>

Andreas Leitgeb wrote:

Suppose, you've got two arrays oa1 and oa2, that you want to join:
Object oa1[]=..., oa2[]=..., oa3[];

Then, first you use: oa3=Arrays.copyOf(oa1,oa1.length+oa2.length);
to get a new array large enough to hold both original arrays,
and already filled with oa1's elements, and then you use:

System.arraycopy(oa2, 0, oa3, oa1.length, oa2.length);

and voila, oa3 contains oa1 and oa2 concatenated.

That's kind of a cool idea. I don't see a concatenate method in Arrays
or System. Joshua Bloch recommends making a utility class to add a few
"missing" generic methods for Collections. The same could be done for
Arrays.

package cljprogrammer;

public class CollectionsUtils {

     public static <T> T[] concat( T[] a1, T[] a2 )
     {
         T[] t = java.util.Arrays.copyOf( a1, a1.length+a2.length );
         System.arraycopy(a2, 0, t, a1.length, a2.length);
         return t;
     }

}

Of course now you need to code up all the primitives too....

jff (just for fun...)