Re: Improved for each loop

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 13 Jul 2009 22:06:54 -0400

Message-ID:

<h3gp80$nuk$1@news.albasani.net>

Roedy Green wrote:

You might generalise that to also permit things like this:

for ( int i: anArray )

for ( int i: anArrayList )

for ( int i: someString )

I think those extensions are safe. If muddled them up with the
existing forms, the body of the loop would generate type errors.

Daniel Pitts wrote:

Not really:

int[] anArray;
for (int i: anArray) // Oops.

List<Integer> anArrayList;
for (int i: anArrayList) // oops.

I guess by "oops" you mean that the syntax is already valid in current Java.
I had a hard time seeing that as "oops", more like "huzzah".

<sscce>
package testit;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public final class LoopGuru
{
   public static void main( String [] args )
   {
     final Random ran = new Random();
     int [] primitivos =
     { ran.nextInt(), ran.nextInt(), ran.nextInt(),
       ran.nextInt(), ran.nextInt(), ran.nextInt(),
     };

     List <Integer> instances =
         new ArrayList <Integer> (primitivos.length);

     System.out.println( "array" );
     System.out.print( "{ " );

     for ( int ix : primitivos )
     {
       System.out.print( ix );
       System.out.print( ", " );
       instances.add( Integer.valueOf( ix ));
     }
     System.out.println( "}" );

     System.out.println( "list" );
     System.out.print( "{ " );

     for ( int ix : instances )
     {
       System.out.print( ix );
       System.out.print( ", " );
     }
     System.out.println( "}" );
   }
}
</sscce>

Output:
array
{ 627089629, 1671919000, -211269067, -241006977, 1094855336, 1531172813, }
list
{ 627089629, 1671919000, -211269067, -241006977, 1094855336, 1531172813, }

--
Lew