Re: Generics - Is this possible?

From:

Hendrik Maryns <gtw37bn02@sneakemail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 21 Apr 2008 12:27:20 +0200

Message-ID:

<fuhq6e$p06$1@newsserv.zdv.uni-tuebingen.de>

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Patricia Shanahan schreef:
| Logan Shaw wrote:
| ...
|> Is there a reason why an enhanced for loop couldn't be built to use
|> either
|> an Iterator or an Iterable?
|>
|> There are cases when we have a priori that an Iterator object exists.
|> For example, some API returns an Iterator. (There are other legit uses.)
|> In those cases, it would nice to be able to use the object at hand.
| ...
|
| Here's a solution that I just worked out for my own use:
|
| import java.util.Iterator;
|
| /**
| * Iterable whose iterator() method returns a
| * specified Iterator.
| * @param <T> The base type of the Iterator and Iterable.
| */
| public class IteratorToIterable<T> implements Iterable<T> {
| private Iterator<T> base;
| /**
| * Create an Iterable whose iterator method returns base.
| * @param base
| */
| public IteratorToIterable(Iterator<T> base){
| this.base = base;
| }
| /**
| * Get the Iterator passed to the constructor. The Iterator
| * should be used only once.
| */
| public Iterator<T> iterator() {
| return base;
| }
| }

I would add

public static <T> Iterable<T> toIterable(Iterator<T> base) {
~ return new IteratorToIterable<T>(base);
}

(this is a pattern much seen in Jakarta Commons)
and then

| public static void main(String[] args) {
| Iterator<Integer> it = getIterator();
| for(Integer i: toIterable(it) ){
| System.out.println(i);
| }
| }

with a proper static import.

One could even just put that method somewhere in the class where one
wants to use it.

H.
- --
Hendrik Maryns
http://tcl.sfs.uni-tuebingen.de/~hendrik/
==================
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