Casting Object[]

Posted: 9/3/2003 10:31:00 PM

java-programmer, Casting Object[] Hi :o)

I've created a useful routine that "appends" an Object on to the end of an
array of Object, creating a new array with slack space if there is not
enough space available (sort of like a light-weight Vector):

public static final Object[] append(Object[] buf, int buf_len, Object addxn,
int slack)
{
Object[] ptr = buf;
if (buf == null || (buf_len + 1) > buf.length)
{
ptr = new Object[buf_len + 1 + slack];
if (buf != null) System.arraycopy(buf, 0, ptr, 0, buf_len);
}
ptr[buf_len] = addxn;
return ptr;
}

Anyway, this works fine, no probs, etc.

I am having problems, however, casting Object[] onto String[] or any other
such cast. Even if, obviously, all the elements of the array are String.

Now, I can state straight off where the problem lies. If I choose a large
enough String[] buffer so that the appended String fits inside it, then the
returned array can be cast back onto String[] - however, if the buffer is
exceeded, and line 6 is executed (creating a new buffer) then it can no
longer be cast back onto String[].

Does that make sense?

Anyway, the question! Is there any way of creating an Object[] array
generically which is of the same type as the original array. In other words,
it would create a new String[] array or Color[] or Rectangle[] or whatever
as appropriate?

Is there a way of doing it by reflection??? (perhaps)

Cheers :o)

And if you don't understand what I going on about, just shout! (hehe) and
I'll try and explain better!

Will

Posted: 9/3/2003 11:06:00 PM

java-programmer >> Casting Object[]

Will Clark wrote:
>
> Anyway, the question! Is there any way of creating an Object[] array
> generically which is of the same type as the original array. In other words,
> it would create a new String[] array or Color[] or Rectangle[] or whatever
> as appropriate?
>

java.lang.reflect.Array.newInstance(Class componentType, int dimension)

Posted: 9/3/2003 11:48:00 PM

java-programmer >> Casting Object[] Thankyou so much!

"David Zimmerman" <email***@***.com> wrote in message
news:yrn5b.54355$email***@***.com...
>
>
> Will Clark wrote:
> >
> > Anyway, the question! Is there any way of creating an Object[] array
> > generically which is of the same type as the original array. In other
words,
> > it would create a new String[] array or Color[] or Rectangle[] or
whatever
> > as appropriate?
> >
>
> java.lang.reflect.Array.newInstance(Class componentType, int dimension)
>