Develop Reference

How to convert "Æàìáûë" to readable cyrillic in Java?

I tryed to get byte and then convert with Utf-8.
byte ptext[] = first_name.getBytes();
Log.i("", new String(ptext,"UTF-8"));
But it's not working .Sorry for my dumbness. I'm very confused.

try {
String s = new String("Æàìáûë".getBytes(StandardCharsets.ISO_8859_1), "Windows-1251");
Files.write(Paths.get("C:/cyrillic.txt"),
("\uFEFF" + s).getBytes(StandardCharsets.UTF_8));
} catch (IOException e) {
e.printStackTrace();
}
Assuming that the editor and compiler are set to UTF-8 to have a correct erroneous string literal.
This treats the characters as single bytes, abusing ISO-8859-1. Then tries the Windows-1251 encoding for Cyrillic (there are others).
This way we have a java String (always in Unicode).
This we'll write to a text file in UTF-8, with a BOM, so Windows Notepad will identify the file as UTF-8.
Writing to any Cyrillic encoding will be no problem.
Жамбыл

Your byte array must have some encoding. The encoding cannot be ASCII if you've got negative values. Once you figure that out, you can convert a set of bytes to a String using:
byte[] bytes = {...}
String str = new String(bytes, "UTF-8"); // for UTF-8 encoding
Log.i("value", str);
There are a bunch of encodings you can use, look at the Charset class in the Sun javadocs..

Seems your original encoding is Cp1251:
byte ptext[] = first_name.getBytes();
Log.i("", new String(ptext, "Cp1251")); // <- put it here
Resulting word is Жамбыл.

How to convert UTF-8 to GBK string in java

I retrieved HTML string from an objective site and within it there is a section
class="f9t" name="Óû§Ãû:ôâÈ»12"
I know it's in GBK encoding, as I can see it from the FF browser display. But I do not know how to convert that name string into a readable GBK string (such as 上海 or 北京).
I am using
String sname = new String(name.getBytes(), "UTF-8");
byte[] gbkbytes = sname.getBytes("gb2312");
String gbkStr = new String( gbkbytes );
System.out.println(gbkStr);
but it's not printed right in GBK text
???¡ì??:????12
I have no clue how to proceed.

You can try this if you already read the name with a wrong encoding and get the wrong name value "Óû§Ãû:ôâÈ»12", as #Karol S suggested:
new String(name.getBytes("ISO-8859-1"), "GBK")
Or if you read a GBK or GB2312 string from internet or a file, use something like this to get the right string at the first place:
BufferedReader r = new BufferedReader(new InputStreamReader(is,"GBK")); name = r.readLine();

Assuming that name.getBytes() returns GBK encoded string it's enough to create string specifying encoding of array of bytes:
new String(gbkString.getBytes(), "GBK");
Regarding to documentation the name of encryption should be GBK.
Sample code:
String gbkString = "Óû§Ãû:ôâÈ»12";
String utfString = new String(gbkString.getBytes(), "GBK");
System.out.println(utfString);
Result (not 100% sure that it's correct :) ):
脫脙禄搂脙没:么芒脠禄12

Encoding troubles with Java

How can I make String Стек look like %D0%A1%D1%82%D0%B5%D0%BA? Which encoding is it? How can I do it with Java? I thought it's UTF-8:
String myString = "Стек";
byte text[] = myString.getBytes();
String value = new String(text, "UTF-8");
System.out.println(value);
But no, I've got Стек in output.

It's not UTF-8, it's URL-like encoding, and you can get it using the URLEncoder class:
String encoded = URLEncoder.encode("Стек");
System.out.println(encoded);
Result:
%D0%A1%D1%82%D0%B5%D0%BA
IDEOne working example

The text that you've shown is Percent encoded or URL encoded.
You can use URLEncoder for converting it to the desired format:
String value = URLEncoder.encode("Стек", "ISO-8859-1");

You can use the URLEncoder class to convert a String to percent encoding:
import java.net.URLEncoder;
System.out.println(URLEncoder.encode("Стек", "utf-8"));
You'll also need to catch UnsupportedEncodingException.

How best to convert a byte[] array to a string buffer

I have a number of byte[] array variables I need to convert to string buffers.
is there a method for this type of conversion ?
Thanks
Thank you all for your responses..However I didn't make myself clear....
I'm using some byte[] arrays pre-defined as public static "under" the class declaration
for my java program. these "fields" are reused during the "life" of the process.
As the program issues status messages, (written to a file) I've defined a string buffer
(mesg_data) that used to format a status message.
So as the program executes
I tried msg2 = String(byte_array2)
I get a compiler error:
cannot find symbol
symbol : method String(byte[])
location: class APPC_LU62.java.LU62XnsCvr
convrsID = String(conversation_ID) ;
example:
public class LU62XnsCvr extends Object
.
.
static String convrsID ;
static byte[] conversation_ID = new byte[8] ;
So I can't use a "dynamic" define of a string variable because the same variable is used
in multiple occurances.
I hope I made myself clear
Thanks ever so much
Guy

String s = new String(myByteArray, "UTF-8");
StringBuilder sb = new StringBuilder(s);

There is a constructor that a byte array and encoding:
byte[] bytes = new byte[200];
//...
String s = new String(bytes, "UTF-8");
In order to translate bytes to characters you need to specify encoding: the scheme by which sequences (typically of length 1,2 or 3) of 0-255 values (that is: sequence of bytes) are mapped to characters. UTF-8 is probably the best bet as a default.

You can turn it to a String directly
byte[] bytearray
....
String mystring = new String(bytearray)
and then to convert to a StringBuffer
StringBuffer buffer = new StringBuffer(mystring)

You may use
str = new String(bytes)
By thewhat the code above does is to create a java String (i.e. UTF-16) with the default platform character encoding.
If the byte array was created from a string encoded in the platform default character encoding this will work well.
If not you need to specify the correct character encoding (Charset) as
String str = new String (byte [] bytes, Charset charset)

It depends entirely on the character encoding, but you want:
String value = new String(bytes, "US-ASCII");
This would work for US-ASCII values.
See Charset for other valid character encodings (e.g., UTF-8)

Java InputStream encoding/charset

Running the following (example) code
import java.io.*;
public class test {
public static void main(String[] args) throws Exception {
byte[] buf = {-27};
InputStream is = new ByteArrayInputStream(buf);
BufferedReader r = new BufferedReader(
new InputStreamReader(is, "ISO-8859-1"));
String s = r.readLine();
System.out.println("test.java:9 [byte] (char)" + (char)s.getBytes()[0] +
" (int)" + (int)s.getBytes()[0]);
System.out.println("test.java:10 [char] (char)" + (char)s.charAt(0) +
" (int)" + (int)s.charAt(0));
System.out.println("test.java:11 string below");
System.out.println(s);
System.out.println("test.java:13 string above");
}
}
gives me this output
test.java:9 [byte] (char)? (int)63
test.java:10 [char] (char)? (int)229
test.java:11 string below
?
test.java:13 string above
How do I retain the correct byte value (-27) in the line-9 printout? And consequently receive the expected output of the System.out.println(s) command (å).

If you want to retain byte values, don't use a Reader at all, ideally. To represent arbitrary binary data in text and convert it back to binary data later, you should use base16 or base64 encoding.
However, to explain what's going on, when you call s.getBytes() that's using the default character encoding, which apparently doesn't include Unicode character U+00E5.
If you call s.getBytes("ISO-8859-1") everywhere instead of s.getBytes() I suspect you'll get back the right byte value... but relying on ISO-8859-1 for this is kinda dirty IMO.

As noted, getBytes() (no-arguments) uses the Java platform default encoding, which may not be ISO-8859-1. Simply printing it should work, provided your terminal and the default encoding match and support the character. For instance, on my system, the terminal and default Java encoding are both UTF-8. The fact that you're seeing a '?' indicates that yours don't match or å is not supported.
If you want to manually encode to UTF-8 on your system, do:
String s = r.readLine();
byte[] utf8Bytes = s.getBytes("UTF-8");
It should give a byte array with {-61, -91}.