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From: Simone on 19 Jul 2010 06:56
Hello,

maybe my question has already been asked here but I couldn't find a
precise answer for now...
Is it possible to customize the way the implicit "toString" method,
invoked e.g. by System.out.print(...), will produce the output string?

If I write the following code:

int[] vector = new int[] {1,2,3,4};
System.out.println( vector );

the output is:

v = [I(a)1d9f953d

corresponding to an internal java information about the object (the
hash code, I believe).
With a "classic" object of a class, I can rewrite the toString()
method and output the string that I want, simply writing e.g.
System.out.println( objectName ). Is there a way to rewrite the
"implicit" toString() method for arrays, so that I can write
System.out.println( "v =" + vector ) and obtain the output: v =
(1,2,3,4) ?

Many thanks in advance.


Simone.
From: Tom Anderson on 19 Jul 2010 07:53
On Mon, 19 Jul 2010, Simone wrote:

> Is there a way to rewrite the "implicit" toString() method for arrays,
> so that I can write System.out.println( "v =" + vector ) and obtain the
> output: v = (1,2,3,4) ?

Sadly not.

The best sticking-plaster is usually to wrap the array in a list:

System.out.println(Arrays.asList(vector));

That method returns a lightweight wrapper around the array that, amongst
other things, implements a more sensible toString.

tom

--
Better to die on your feet than live on your knees. -- Emiliano Zapata
From: Simone on 22 Jul 2010 17:49
First, thank you Stefan and Tom for your answers. I apologize for
answering so late.

I also noticed that the solution with Arrays.asList(vector) works only
if vector is an array of a wrapper class and not if it's an array of a
primitive type, in which case the output is, again, the hash code of
the array.

I'm using the solution Arrays.asList(vector) for now, maybe I'll write
a specific method... Or I'll write a wrapper class for my array with
my specific toString... unfortunately I'll lose the chance to use the
brackets for referring to elements.


Simone.


On 19 Lug, 13:53, Tom Anderson <t...(a)urchin.earth.li> wrote:
> On Mon, 19 Jul 2010, Simone wrote:
> > Is there a way to rewrite the "implicit" toString() method for arrays,
> > so that I can write System.out.println( "v =" + vector ) and obtain the
> > output: v = (1,2,3,4) ?
>
> Sadly not.
>
> The best sticking-plaster is usually to wrap the array in a list:
>
> System.out.println(Arrays.asList(vector));
>
> That method returns a lightweight wrapper around the array that, amongst
> other things, implements a more sensible toString.
>
> tom
>
> --
> Better to die on your feet than live on your knees. -- Emiliano Zapata

From: Alan Gutierrez on 22 Jul 2010 18:12
Simone wrote:
> First, thank you Stefan and Tom for your answers. I apologize for
> answering so late.
>
> I also noticed that the solution with Arrays.asList(vector) works only
> if vector is an array of a wrapper class and not if it's an array of a
> primitive type, in which case the output is, again, the hash code of
> the array.
>
> I'm using the solution Arrays.asList(vector) for now, maybe I'll write
> a specific method... Or I'll write a wrapper class for my array with
> my specific toString... unfortunately I'll lose the chance to use the
> brackets for referring to elements.

Don't top post.

Not sure what you're on about:

import java.util.Arrays;

public class AsList {
public static void main(String[] args) {
System.out.println(Arrays.asList(1, 2, 3));
}
}

[alan(a)postojna ~]$ javac AsList.java
[alan(a)postojna ~]$ java AsList
[1, 2, 3]
[alan(a)postojna ~]$

--
Alan Gutierrez - alan(a)blogometer.com - http://twitter.com/bigeasy
From: John B. Matthews on 22 Jul 2010 18:14
In article
<09545a75-b1e3-4465-ad92-d1c9ea77c261(a)5g2000yqz.googlegroups.com>,
Simone <simbo1980(a)gmail.com> wrote:

> I also noticed that the solution with Arrays.asList(vector) works only
> if vector is an array of a wrapper class and not if it's an array of a
> primitive type, in which case the output is, again, the hash code of
> the array.

Would this be an usable alternative?

int[] intArray = new int[]{ 1, 2, 3, 4 };
System.out.println(Arrays.toString(intArray));

For better or worse, the square brackets are included:

[1, 2, 3, 4]

--
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>
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