Develop Reference

Java encode special character in a String with UTF-8 character

String original = "This is my string valúe";
I'm trying to encode the above string to UTF-8 equivalent but to replace only special character (ú) with -- "&#250 ;" in this case.
I've tried using the below but I get an error:
Input is not proper UTF-8, indicate encoding !Bytes: 0xFA 0x20 0x63 0x61
Code:
String original = new String("This is my string valúe");
byte ptext[] = original.getBytes("UTF-8");
String value = new String(ptext, "UTF-8");
System.out.println("Output : " + value);
This is my string valúe

You could use String.replace(CharSequence, CharSequence) and formatted io like
String original = "This is my string valúe";
System.out.printf("Output : %s%n", original.replace("ú", "ú"));
Which outputs (as I think you wanted)
Output : This is my string valúe

You seem to want to use XML character entities.
Appache Commons Lang has a method for this (in StringEscapeUtils).

Im trying to encode the above string to UTF-8 equivalent but to replace only >special character ( ú ) with -- "&#250 ;" in this case.
I'm not sure what encoding "&#250 ;" is but have you tried looking at the URLEncoder class? It won't encode the string exactly the way you asked but it gets rid of the spooky character.

Could you please try the below lines:
byte ptext[] = original.getBytes("UTF8");
String value = new String(ptext, "UTF8");

How to convert String to byte without changing?

I need a solution to convert String to byte array without changing like this:
Input:
String s="Test";
Output:
String s="Test";
byte[] b="Test";
When I use
s.getBytes();
then the reply is
"[B#428b76b8"
but I want the reply to be
"Test"

You should always make sure serialization and deserialization are using the same character set, this maps characters to byte sequences and vice versa. By default String.getBytes() and new String(bytes) uses the default character set which could be Locale specific.
Use the getBytes(Charset) overload
byte[] bytes = s.getBytes(Charset.forName("UTF-8"));
Use the new String(bytes, Charset) constructor
String andBackAgain = new String(bytes, Charset.forName("UTF-8"));
Also Java 7 added the java.nio.charset.StandardCharsets class, so you don't need to use dodgy String constants anymore
byte[] bytes = s.getBytes(StandardCharsets.UTF_8);
String andBackAgain = new String(bytes, StandardCharsets.UTF_8);

You can revert back using
String originalString = new String(b, "UTF-8");
That should get you back your original string. You don't want the bytes printed out directly.

You may try the following code snippet -
String string = "Sample String";
byte[] byteArray = string.getBytes();

In general that's probably not what you want to do, unless you're serializing or transmitting the data. Also, Java strings are UTF-16 rather than UTF-8, which what more like what you're expecting. If you really do want/need this then this should work:
String str = "Test";
byte[] raw = str.getBytes(new Charset("UTF-8", null));

JAVA: failing to get encrypted data in string using xor

I was trying to print encrypted text using string perhaps i was wrong somewhere. I am doing simple xor on a plain text. Coming encrypted text/string i am putting in a C program and doing same xor again to get plain text again.
But in between, I am not able to get proper string of encrypted text to pass in C
String xorencrypt(byte[] passwd,int pass_len){
char[] st = new char[pass_len];
byte[] crypted = new byte[pass_len];
for(int i = 0; i<pass_len;i++){
crypted[i] = (byte) (passwd[i]^(i+1));
st[i] = (char)crypted[i];
System.out.println((char)passwd[i]+" "+passwd[i] +"= " + (char)crypted[i]+" "+crypted[i]);/* characters are printed fine but problem is when i am convering it in to string */
}
return st.toString();
}
I don't know if any kind of encoding also needed because if i did so how I will decode and decrypt from C program.
example if suppose passwd = bond007
then java program should return akkb78>
further C program will decrypt akkb78> to bond007 again.

Use
return new String(crypted);
in that case you don't need st[] array at all.
By the way, the encoded value for bond007 is cmm`560 and not what you posted.
EDIT
While solution above would most likely work in most java environments, to be safe about encoding,
as suggested by Alex, provide encoding parameter to String constructor.
For example if you want your string to carry 8-bit bytes :
return new String(crypted, "ISO-8859-1");
You would need the same parameter when getting bytes from your string :
byte[] bytes = myString.getBytes("ISO-8859-1")
Alternatively, use solution provided by Alex :
return new String(st);
But, convert bytes to chars properly :
st[i] = (char) (crypted[i] & 0xff);
Otherwise, all negative bytes, crypted[i] < 0 will not be converted to char properly and you get surprising results.

Change this line:
return st.toString();
with this
return new String(st);

How to convert UTF8 string to UTF16

I'm getting a UTF8 string by processing a request sent by a client application. But the string is really UTF16. What can I do to get it into my local string is a letter followed by \0 character? I need to convert that String into UTF16.
Sample received string: S\0a\0m\0p\0l\0e (UTF8).
What I want is : Sample (UTF16)
FileItem item = (FileItem) iter.next();
String field = "";
String value = "";
if (item.isFormField()) {
try{
value=item.getString();
System.out.println("====" + value);
}

The bytes from the server are not UTF-8 if they look like S\0a\0m\0p\0l\0e. They are UTF-16. You can convert UTF16 bytes to a Java String with:
byte[] bytes = ...
String string = new String(bytes, "UTF-16");
Or you can use UTF-16LE or UTF-16BE as the character set name if you know the endian-ness of the byte stream coming from the server.
If you've already (mistakenly) constructed a String from the bytes as if it were UTF-8, you can convert to UTF-16 with:
string = new String(string.getBytes("UTF-8"), "UTF-16");
However, as JB Nizet points out, this round trip (bytes -> UTF-8 string -> bytes) is potentially lossy if the bytes weren't valid UTF-8 to start with.

I propose the following solution:
NSString *line_utf16[ENOUGH_MEMORY_SIZE];
line_utf16= [NSString stringWithFormat: #"%s", line_utf8];
ENOUGH_MEMORY_SIZE is at least twice exceeds memory used for line_utf8
I suppose memory for
line_utf16
has to be dynamically or statically allocated at least twice of the size of
line_utf8.
If you run into similar problem please add a couple of sentences!

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)