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Convert Unicode to UTF-8

My question may already have been answered on StackoverFlow, but I can't find it.
My problem is simple: I request data via an API, and the data returned have unicode characters, for example:
"SpecialOffer":[{"title":"Offre Vente Priv\u00e9e 1 jour 2019 2020"}]
I need to convert the "\u00e9e" to "é".
I cant't make a "replaceAll", because I cannot know all the characters that there will be in advance.
I try this :
byte[] utf8 = reponse.getBytes("UTF-8")
String string = new String(utf8, "UTF-8");
But the string still has "\u00e9e"
Also this :
byte[] utf8 = reponse.getBytes(StandardCharsets.UTF_8);
String string = new String(utf8, StandardCharsets.UTF_8);
Also tried this :
string = string.replace("\\\\", "\\");
byte[] utf8Bytes = null;
String convertedString = null;
utf8Bytes = string.getBytes("UTF8") -- Or StandardCharsets.UTF_8 OR UTF-8 OR UTF_8;
convertedString = new String(utf8Bytes, "UTF8") -- Or StandardCharsets.UTF_8 OR UTF-8 OR UTF_8;;
System.out.println(convertedString);
return convertedString;
But it doesn't work either.
I tested other methods but I think I deleted everything like that didn't work so I can't show them to you here.
I am sure there is a very simple method, but I should not search with the right vocabulary on the internet. Can you help me please ?
I wish you a very good day, and thank you very much in advance.

The String.getBytes method requires a valid Charset [1]
From the javadoc [2] the valid cases are
US-ASCII
ISO-8859-1
UTF-8
UTF-16BE
UTF-16LE
UTF-16
So you need to use UTF-8 in the getBytes method.
[1] https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#getBytes-java.nio.charset.Charset-
[2] https://docs.oracle.com/javase/8/docs/api/java/nio/charset/Charset.html

You can use small json library
String jsonstring = "{\"SpecialOffer\":[{\"title\":\"Offre Vente Priv\\u00e9e 1 jour 2019 2020\"}]}";
JsonValue json = JsonParser.parse(jsonstring);
String value = json.asObject()
.first("SpecialOffer").asArray().get(0)
.asObject().first("title").asStringLiteral().stringValue();
System.out.println(" result: " + value);
or
String text = "Offre Vente Priv\\u00e9e 1 jour 2019 2020";
System.out.println(" result: " + JsonEscaper.unescape(text));

The problem that I had not seen, is that the API did not return me "\u00e9e" but "\\u00e9e" as it was a character sequence and not a unicode character!
So I have to recreate all the unicodes, and everything works fine!
int i=0, len=s.length();
char c;
StringBuffer sb = new StringBuffer(len);
while (i < len) {
c = s.charAt(i++);
if (c == '\\') {
if (i < len) {
c = s.charAt(i++);
if (c == 'u') {
// TODO: check that 4 more chars exist and are all hex digits
c = (char) Integer.parseInt(s.substring(i, i+4), 16);
i += 4;
} // add other cases here as desired...
}
} // fall through: \ escapes itself, quotes any character but u
sb.append(c);
}
return sb.toString();
Find this solution here:
Java: How to create unicode from string "\u00C3" etc

Converting byte array to String Java

I wish to convert a byte array to String but as I do so, my String has 00 before every digit got from the array.
I should have got the following result: 49443a3c3532333437342e313533373936313835323237382e303e
But I have the following:
Please help me, how can I get the nulls away?
I have tried the following ways to convert:
xxxxId is the byteArray
String xxxIdString = new String(Hex.encodeHex(xxxxId));
Thank you!

Try something like this:
String s = new String(bytes);
s = s.replace("\0", "")
It's also posible, that the string will end after the first '\0' received, if thats the case, first iterate through the array and replace '\0' with something like '\n' and do this:
String s = new String(bytes);
s = s.replace("\n", "")
EDIT:
use this for a BYTE-ARRAY:
String s = new String(bytes, StandardCharsets.UTF_8);
use this for a CHAR:
String s = new String(bytes);

Try below code:
byte[] bytes = {...}
String str = new String(bytes, "UTF-8"); // for UTF-8 encoding
please have a look here- How to convert byte array to string and vice versa?

In order to convert Byte array into String format correctly, we have to explicitly create a String object and assign the Byte array to it.
String example = "This is an example";
byte[] bytes = example.getBytes();
String s = new String(bytes);

Encode/decode hex to utf-8 string

Working on web application which accepts all UTF-8 character's including greek characters following are strings that i want to convert to hex.
Following are different language string which are not working in my current code
ЫЙБПАРО Εγκυκλοπαίδεια éaös Größe Größe
Following are hex conversions by javascript function mentioned below
42b41941141f41042041e 3953b33ba3c53ba3bb3bf3c03b13af3b43b53b93b1 e961f673 4772c3192c2b6c3192c217865 4772f6df65
Javascript function to convert above string to hex
function encode(string) {
var str= "";
var length = string.length;
for (var i = 0; i < length; i++){
str+= string.charCodeAt(i).toString(16);
}
return str;
}
Here it is not giving any error to convert but at java side I'm unable to parse such string used following java code to convert hex
public String HexToString(String hex){
StringBuilder finalString = new StringBuilder();
StringBuilder tempString = new StringBuilder();
for( int i=0; i<hex.length()-1; i+=2 ){
String output = hex.substring(i, (i + 2));
int decimal = Integer.parseInt(output, 16);
finalString.append((char)decimal);
tempString.append(decimal);
}
return finalString.toString();
}
It throws error while parsing above hex string giving parse exception.
Suggest me the solution

Javascript works with 16-bit unicode characters, therefore charCodeAt might return any number between 0 and 65535. When you encode it to hex you get strings from 1 to 4 chars, and if you simply concatenate these, there's no way for the other party to find out what characters have been encoded.
You can work around this by adding delimiters to your encoded string:
function encode(string) {
return string.split("").map(function(c) {
return c.charCodeAt(0).toString(16);
}).join('-');
}
alert(encode('größe Εγκυκλοπαίδεια 维'))

How to convert into cyrillic

Good day.
I got string like this from server
\u041a\u0438\u0441\u0435\u043b\u0435\u0432 \u0410\u043d\u0434\u0440\u0435\u0439
I need to convert it into cyrillic cp-1251 string.
How do i do it? Thank you.

If that is a literal sequence of characters that must decoded, you'll need to first start with something like this (assuming your input is in the string input):
StringBuffer decodedInput = new StringBuffer();
Matcher match = Pattern.compile("\\\\u([0-9a-fA-F]{4})| ").matcher(input);
while (match.find()) {
String character = match.group(1);
if (character == null)
decodedInput.append(match.group());
else
decodedInput.append((char)Integer.parseInt(character, 16));
}
At this point, you should have java string representation of your input in decodedInput.
If your system supports the cp-1251 charset, you can then convert that to cp-1251 with something like this:
Charset cp1251charset = Charset.forName("cp-1251");
ByteBuffer output = cp1251charset.encode(decodedInput.toString());

How to get encoded version of string (e.g. \u0421\u043b\u0443\u0436\u0435\u0431\u043d\u0430\u044f)

How to get encoded version of string (e.g. \u0421\u043b\u0443\u0436\u0435\u0431\u043d\u0430\u044f) using Java?
EDIT:
I guess the question is not very clear... Basically what I want is this:
Given string s="blalbla" I want to get string "\uXXX\uYYYY"

You will need to extract each code point/unit from the String and encode it yourself. The following works for all Strings even if the individual linguistic characters within the String are composed of digraphs or ligatures.
public String getUnicodeEscapes(String aString)
{
if (aString != null && aString.length() > 0)
{
int length = aString.length();
StringBuilder buffer = new StringBuilder(length);
for (int ctr = 0; ctr < length; ctr++)
{
char codeUnit = aString.charAt(ctr);
String hexString = Integer.toHexString(codeUnit);
String padAmount = "0000".substring(hexString.length());
buffer.append("\\u");
buffer.append(padAmount);
buffer.append(hexString);
}
return buffer.toString();
}
else
{
return null;
}
}
The above produces output as dictated by the Java Language Specification on Unicode escapes, i.e. it produces output of the form \uxxxx for each UTF-16 code unit. It addresses supplementary characters by producing a pair of code units represented as \uxxxx\uyyyy.
The originally posted code has been modified to produce Unicode codepoints in the format U+FFFFF:
public String getUnicodeCodepoints(String aString)
{
if (aString != null && aString.length() > 0)
{
int length = aString.length();
StringBuilder buffer = new StringBuilder(length);
for (int ctr = 0; ctr < length; ctr++)
{
char ch = aString.charAt(ctr);
if (Character.isLowSurrogate(ch))
{
continue;
}
else
{
int codePoint = aString.codePointAt(ctr);
String hexString = Integer.toHexString(codePoint);
String zeroPad = Character.isHighSurrogate(ch) ? "00000" : "0000";
String padAmount = zeroPad.substring(hexString.length());
buffer.append(" U+");
buffer.append(padAmount);
buffer.append(hexString);
}
}
return buffer.toString();
}
else
{
return null;
}
}
The gruntwork is done by the String.codePointAt() method which returns the Unicode codepoint at a particular index. For a String instance composed of combinational characters, the length of the String instance will not be the length of the number of visible characters, but the number of actual Unicode codepoints. For example, क and ् combine to form क् in Devanagari, and the above function will rightfully return U+0915 U+094d without any fuss as String.length() will return 2 for the combined character. Strings with supplementary characters will be with single codepoints for the individual characters - 𝒥𝒶𝓋𝒶𝓈𝒸𝓇𝒾𝓅𝓉 (the page will not display this String literal correctly, but you can copy this just fine; it should be Javascript but written using the supplementary character set for Mathematical alphanumeric symbols) will return U+1d4a5 U+1d4b6 U+1d4cb U+1d4b6 U+1d4c8 U+1d4b8 U+1d4c7 U+1d4be U+1d4c5 U+1d4c9.

public static void main(String[] args) {
Charset charset = Charset.forName("UTF-8");
CharsetDecoder decoder = charset.newDecoder();
CharsetEncoder encoder = charset.newEncoder();
try {
ByteBuffer bbuf = encoder.encode(CharBuffer.wrap("\u0421\u043b\u0443\u0436\u0435\u0431\u043d\u0430\u044f"));
CharBuffer cbuf = decoder.decode(bbuf);
String s = cbuf.toString();
System.out.println(s);
} catch (CharacterCodingException e) {
e.printStackTrace();
}
}

I'm not aware of a build-in solution, so:
StringBuilder builder = new StringBuilder();
for(int i=0; i<yourString.length(); i++) {
builder.append(String.format("\\u%04x", yourString.charAt(i)));
}
String encoded = builder.toString();
Edit: sry, I thought you wanted to get the String encoded to \uXXXX expressions ...

You didn't saying what encoding you are after, but based on the tag I'm assuming you want the UTF-8 encoding. Here's how:
byte[] utf8 =
"\u0421\u043b\u0443\u0436\u0435\u0431\u043d\u0430\u044f".getBytes("UTF-8");
You can then write a simple loop to output the bytes in utf8 in hexadecimal or decimal ... or do something else with them.

System.out.println ("\u0421\u043b\u0443\u0436\u0435\u0431\u043d\u0430\u044f");
works like a charm for me:
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