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How can I reverse a given string without using String or StringBuffer
class method.

Amit Jain <> writes:

> How can I reverse a given string without using String or StringBuffer
> class method.

1. Why would you?
2. What String will you reverse if you don't use String?
And how will you represent the result without using a String?
3. Are you thinking of extracting the chars into an array and
reversing them there? Take care with multi-char Unicode characters

/L
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"Lasse Reichstein Nielsen" <> wrote in message
news:...
> Amit Jain <> writes:
>
>> How can I reverse a given string without using String or StringBuffer
>> class method.
>
> 1. Why would you?

Because it's on his homework, of course.

On Mon, 08 Oct 2007 12:19:36 -0700, Amit Jain <>
wrote, quoted or indirectly quoted someone who said :

>How can I reverse a given string without using String or StringBuffer
>class method.

This obviously an artificial exercise since no one in their right mind
would avoid the built-in StringBuffer/StringBuilder/String methods.

The basic idea is a create char array the correct length, the fill it
one by one from your original string in a loop. Then when you are
done you convert the char[] to a String.

See http://mindprod.com/jgloss/conversion.html
--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

Amit Jain wrote:
> How can I reverse a given string without using String or StringBuffer
> class method.
>
What is the sound of one hand clapping?
You can't reverse a string unless you have a string, now can you?

If you already have a string, you can *print* the reverse if it by
counting backward from the end of it, and printing each character along
the way.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>

Amit Jain wrote:
> How can I reverse a given string without using String or StringBuffer
> class method.

new StringBuilder( givenString ).reverse().toString();


piotr

Daniel Pitts wrote:
> Amit Jain wrote:
>> How can I reverse a given string without using String or StringBuffer
>> class method.
>>
> What is the sound of one hand clapping?

Whoosh?

> If you already have a string, you can *print* the reverse if it by
> counting backward from the end of it, and printing each character along
> the way.

That way some methods of String will still be used indirectly (when
allowed, I prefer my earlier suggestion).

The only way I know to achieve the result without touching any of String
methods is to reflectively access String's internals (i.e. value,
offset, and count fields). And then create a new String (we can use
constructors, they are not a methods) with the reversed chars of the
value array copy. That way is of course never guarantied to work, and
is rather awful hack than the solution. Thus, one should even try to do
that!


piotr

Piotr Kobzda wrote:
> ... Thus, one should even try to do
> that!

NO-ONE of course!


piotr

On Wed, 10 Oct 2007 11:52:11 +0200, Piotr Kobzda <>
wrote, quoted or indirectly quoted someone who said :

>new StringBuilder( givenString ).reverse().toString();

I think the intent of the exercise is to solve it without using a
built-in reverse method. The prof wants his students to do a simple
char by char string building exercise.

--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

On 10 Oct, 12:37, Roedy Green <see_webs...@mindprod.com.invalid>
wrote:
> On Wed, 10 Oct 2007 11:52:11 +0200, Piotr Kobzda <pi...@gazeta.pl>
> wrote, quoted or indirectly quoted someone who said :
>
> >new StringBuilder( givenString ).reverse().toString();
>
> I think the intent of the exercise is to solve it without using a
> built-in reverse method. The prof wants his students to do a simple
> char by char string building exercise.
>
> --
> Roedy Green Canadian Mind Products
> The Java Glossaryhttp://mindprod.com

Hey Amit are you still with us?

The standard recursive and fun way to do this is (in pseudo-code)

if length of string is 1, return string
else
return reverse(string without first character) joined with first
character