Re: Array of Objects - Qsn

From:

blmblm@myrealbox.com <blmblm@myrealbox.com>

Newsgroups:

comp.lang.java.programmer

Date:

26 May 2007 16:40:43 GMT

Message-ID:

<5br68aF2rs186U1@mid.individual.net>

In article <1180116278.470507.280190@q66g2000hsg.googlegroups.com>,
Daniel Pitts <googlegroupie@coloraura.com> wrote:

On May 25, 10:30 am, "Oliver Wong" <o...@castortech.com> wrote:

"Mike Schilling" <mscottschill...@hotmail.com> wrote in message

news:Z7E5i.6841$4Y.6769@newssvr19.news.prodigy.net...

<blm...@myrealbox.com> wrote in message
news:5bog4pF2u1ladU2@mid.individual.net...

In article <1180107837.234928@news1nwk>,
Eric Sosman <Eric.Sos...@Sun.COM> wrote:

blm...@myrealbox.com wrote On 05/25/07 07:19,:

is
there some neat trick I don't know for creating an array of
objects without an explicit loop?

Thing[] thing = new Thing[] {
    new Thing(42),
    new Thing("abc"),
    new SubclassOfThing(new Date()),
};

Well, you got me on that one! But I can't think how to state the
question I actually had in mind more precisely, so -- oh well.

I think you're saying that there's no way to create a array of objects
whose size is determined at run-time without a loop.

Yes, thanks! -- well, except that I'm not saying there isn't a way,
but asking whether there is one, and indeed there appear to be
several, if you're clever and/or know the Collections class better
than I do:

public class Test4 {
  public static Object[]
makeArrayOfObjectsWhoseSizeIsDeterminedAtRuntimeWithoutALoop(int size) {
    if (size < 0) {
      throw new IllegalArgumentException();
    }
    if (size == 0) {
      return new Object[0];
    }
    Object[] returnValue = new Object[size];
    returnValue[0] = new Object();

System.arraycopy(makeArrayOfObjectsWhoseSizeIsDeterminedAtRuntimeWithoutALoop(size

- 1), 0, returnValue, 1, size - 1);
    return returnValue;
  }

}

    Or, since array indexes must be java integer, and there's a finite
number of them:

public class Test4 {
  public static Object[]
makeArrayOfObjectsWhoseSizeIsDeterminedAtRuntimeWithoutALoop(
      int size) {
    switch (size) {
    case 0:
      return new Object[] {};
    case 1:
      return new Object[] { new Object() };
    case 2:
      return new Object[] { new Object(), new Object() };

    /*etc.*/

    default:
      throw new IllegalArgumentException();
    }
  }

}

    - Oliver

Collections.nCopies(count, new Object()).toArray();

--
B. L. Massingill
ObDisclaimer: I don't speak for my employers; they return the favor.