convert byte[] to actual string value

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IveCal - 20 May 2006 09:03 GMT

Hello... How are we going to convert byte[] to it's actual string
value?

ex.

String source = "china";
byte[] bytes = source.getBytes();

// CONVERT the bytes ARRAY to it's actual string value "china"

Please do reply... Thank you very much . . .

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Jan Peter Stotz - 20 May 2006 09:44 GMT

IveCal schrieb:

> Hello... How are we going to convert byte[] to it's actual string
> value?

> String source = "china";
> byte[] bytes = source.getBytes();
>
> // CONVERT the bytes ARRAY to it's actual string value "china"

String source2 = new String(bytes);

Jan

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Mike Schilling - 20 May 2006 15:43 GMT

> IveCal schrieb:
>
[quoted text clipped - 7 lines]
>
> String source2 = new String(bytes);

The conversions

String -> byte[]

and

byte[] -> String

both require an encoding, that is a mapping between a char and one or more
bytes. Common encodings are UTF-16, UTF-8, ASCII, ISO-8851-1, etc. The
methods used above, String.getBytes() and new String(byte[]), use the
default encoding for your Java installation, which might or might not be
what you want, particularly because it might not include all characters. As
a rule I've made for myself, I never use the default encoding. Unless the
situation calls for a specific encoding, say the one specified in the header
of an XML document, I always use UTF-8, because it combines representing
ASCII characters efficiently with being able to represent all characters.

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Dražen Gemić - 20 May 2006 15:58 GMT

> IveCal schrieb:
>
[quoted text clipped - 7 lines]
>
> String source2 = new String(bytes);

I don't know what does the "actual" mean here. Keep in mind that
the strings are UNICODE.

DG

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Chris Smith - 20 May 2006 18:46 GMT

> Hello... How are we going to convert byte[] to it's actual string
> value?
[quoted text clipped - 5 lines]
>
> // CONVERT the bytes ARRAY to it's actual string value "china"

The first thing you must realize is that there IS no actual string value
for a byte array. There are any number of possible strings that could
be meant by that byte array. Which you get depends on the character
encoding, which is essentially a set of rules for converting characters
to bytes and vice versa.

When you call getBytes() on a String object, the platform default
character encoding is used. The platform default encoding is not
defined by any specification, though it will generally be chosen
consistently withing a single operating system and locale combination.

You can try top recover a String according to the platform default
encoding with:

String s = new String(bytes);

That will work IF the operating system AND the locale are the same as
they were when you converted the String to bytes in the first place.
However, if someone tries to convert that byte[] to a String on a
different operating system, or with a different locale (which can be as
simple as setting the LANG environment variable in any UNIX-like system)
they may well get something completely unintelligible.

The safer way to do it is to pick an encoding and stick with it:

String source = "china";
byte[] bytes = source.getBytes("UTF-8");
String s = new String(bytes, "UTF-8");

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Dale King - 22 May 2006 03:18 GMT

> You can try top recover a String according to the platform default
> encoding with:
[quoted text clipped - 3 lines]
> That will work IF the operating system AND the locale are the same as
> they were when you converted the String to bytes in the first place.

I know you know this Chris, but it is important to point out that for it
to work the platform default encoding must support all the characters
in the string which is not necessarily true.

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Dale King

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convert byte[] to actual string value

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