Re: casting error on ArrayList

Thanks James. Took you advice and change it to return a List object.

"James Perkins" <jrperkinsjr@xxxxxxxxx> wrote in message
news:<mailman.2262.1253030380.1811.java400-l@xxxxxxxxxxxx>...

Lim,
IIRC you are fairly new to Java. I am by no means a Java expert, but

I've

taught myself and been there so I thought I would give you a few tips.

Firstly, always try to use the most generic type possible. So, your
ArrayList should be a List, e.g. List<String> rs = new

ArrayList<String>();.

With a number as small as 20 there is no real need to construct it

with that

size.

If it were me I would probably also not return an array of strings,

but

return a collection of type string. If you are worried about it be

immutable

look at Collections.unmodifiableList().

Now, all that being said if you still need to return an array all you

need

to do is rs.toArray(new String[0]). This has to do with generics. The
default List.toArray() method will only return an array of objects.

The

List.toArray(T[]) is used to return the generic type. Without looking

at the

code I couldn't tell you why it's designed like that, but Joshua Bloch

had a

lot to do with the Collections library, so I trust there may be a good
reason.

At any rate I hope this helps. Let me know if you want any clearer
clarification.

--
James R. Perkins
http://twitter.com/the_jamezp


On Tue, Sep 15, 2009 at 06:49, hockchai Lim
<lim.hock-chai@xxxxxxxxxxxxxxx>wrote:

I'm getting a cast error "java.lang.ClassCastException:

[Ljava.lang.Object;

incompatible with [Ljava.lang.String;" and not sure why and how to

resolve

it. Help. . . ..

ArrayList<String> rs = new ArrayList<String>( 20 );

String str;

bin= new BufferedReader(new

InputStreamReader(process.getInputStream()));

while ((str = bin.readLine()) != null) {

rs.add(str);

}


return (String[]) rs.toArray(); // =======> Getting the casting

error:

}


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