Hex to String Conversion

Question

I have string in controller which contains some Hex character. I want to convert that character in string so that I can save it. Can anyone help?

Thanks in advance.

Answer 1

To convert from a String to a Hex value, use the EncodingUtil class.

To convert from Hex to a String, check out this thread in the Community Forum: http://boards.developerforce.com/t5/Apex-Code-Development/Method-to-convert-Hex-to-String-or-blob/td-p/187747. Here's the code posted there (see below):

// convert Hex to UTF-8 (now works with multibyte locales!)
// http://boards.developerforce.com/t5/Apex-Code-Development/Method-to-convert-Hex-to-String-or-blob/td...
private static Map < String, Integer > hexMap = new Map < String, Integer > ();
static{
  hexMap.put('0', 0);
  hexMap.put('1', 1);
  hexMap.put('2', 2);
  hexMap.put('3', 3);
  hexMap.put('4', 4);
  hexMap.put('5', 5);
  hexMap.put('6', 6);
  hexMap.put('7', 7);
  hexMap.put('8', 8);
  hexMap.put('9', 9);
  hexMap.put('A', 10);
  hexMap.put('B', 11);
  hexMap.put('C', 12);
  hexMap.put('D', 13);
  hexMap.put('E', 14);
  hexMap.put('F', 15);
  hexMap.put('a', 10);
  hexMap.put('b', 11);
  hexMap.put('c', 12);
  hexMap.put('d', 13);
  hexMap.put('e', 14);
  hexMap.put('f', 15);
}

public class UTFException extends Exception{
}

public static List < Integer > hexToInt(String hex) {
  List < Integer > retVal = new List < Integer > ();
  Integer i = 0;
  while(i < hex.length()) {

    // http://en.wikipedia.org/wiki/UTF-8
    integer numberOfBytes = 1;
    integer byte1 = 0,
    byte2 = 0,
    byte3 = 0,
    byte4 = 0;
    integer utfCode = 0;
    byte1 = (hexMap.get(hex.substring(i, i + 1)) * 16) + (hexMap.get(hex.substring(i + 1, i + 2)));

    //invalid sequences for byte1
    if(byte1 >= 128 && byte1 <= 191) {
      throw new UTFException('UTF-8:Continuation byte as first byte');
    }
    if(byte1 >= 192 && byte1 <= 193) {
      throw new UTFException('UTF-8:Invalid 2-byte sequence');
    }
    if(byte1 >= 245) {
      throw new UTFException('UTF-8:Invalid 4,5 or 6-byte sequence');
    }

    if(byte1 >= 192) {
      numberOfBytes = 2;
      byte2 = (hexMap.get(hex.substring(i + 2, i + 2 + 1)) * 16) + (hexMap.get(hex.substring(i + 2 + 1, i + 2 + 2)));
    }
    if(byte1 >= 224) {
      numberOfBytes = 3;
      byte3 = (hexMap.get(hex.substring(i + 4, i + 4 + 1)) * 16) + (hexMap.get(hex.substring(i + 4 + 1, i + 4 + 2)));
    }
    if(byte1 >= 240) {
      numberOfBytes = 4;
      byte4 = (hexMap.get(hex.substring(i + 6, i + 6 + 1)) * 16) + (hexMap.get(hex.substring(i + 6 + 1, i + 6 + 2)));
    }
    if(numberOfBytes == 1) {
      utfCode = byte1;
    } else if(numberOfBytes == 2) {
      utfCode = Math.mod(byte1, 32) * 64 + Math.mod(byte2, 64);
    } else if(numberOfBytes == 3) {
      utfCode = Math.mod(byte1, 16) * 64 * 64 + Math.mod(byte2, 64) * 64 + Math.mod(byte3, 64);
    } else if(numberOfBytes == 4) {
      utfCode = Math.mod(byte1, 8) * 64 * 64 * 64 + Math.mod(byte2, 64) * 64 * 64 + Math.mod(byte3, 64) * 64 + Math.mod(byte4, 64);
    }

    retVal.add(utfCode);
    i += 2 * numberOfBytes;
  }
  return retVal;
}

public static Blob HexToUTF(string hex) {
  string text = String.fromCharArray(hexToInt(hex));
  return Blob.valueOf(text);
}

Answer 2

It can be done with fromCharArray method.

(1) Do a math to transfer Hex to Dec
(2) Convert Dec to Ascii

Here is an example code:

List<Integer> charArray = new List<Integer>();
charArray.add(60);
System.debug(String.fromCharArray(charArray));

Ref:

http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_System_String_fromCharArray.htm

Answer 3

I found out that EncodingUtil.urlEncode('myString', 'UTF-8') method seems to have the same effect.

Please check it up.

string ch = 'é';
string result = EncodingUtil.urlEncode(ch, 'UTF-8');
system.debug('*** result: '+result);

This would print the following result: %C3%A9

Answer 4

I was facing same requirement so I built my own code.

1. Do a math to transfer Hex to Dec

2. Convert Dec to Ascii

public class Hexa_2_string {
    /*
     * Developer Name : Teekam singh
     * Functionality: Conversion of hexadecimal to string 
     * version : 1.0.1 
     */
        
    public static void hexatostring(){
        //take input in hexadecimal number
        String hex = '576f726c6427732073696d706c657374206f6e6c696e65207465787420746f2068657861646563696d616c';
        String output = '';
        for(integer i=0; i<hex.length(); i+=2){
            String subtype;
            if(i+2 > hex.length()){
                subtype = hex.substring(i, i+1);                
            }else{
                subtype = hex.substring(i, i+2);
            }
            
            Integer result = convert2decimal(subtype);
            //System.debug('inner value is '+result);
            string str = String.fromCharArray(new Integer[]{result});
            //System.debug('str is '+str);
            output +=str;
            //System.debug('temp '+temp);
        }
        
        System.debug('final is '+ output);        
    }
    /*
     * This function will convert hexadecimal to decimal
     */
    public static integer convert2decimal(String hex){
        
        String rev = hex.reverse();
        String[] hexValue = rev.split('');
        integer base = 0;   
        integer result = 0;
        Map<String,Integer> mymap = convertCharintonum();
        for(Integer index = 0; index < hexValue.size(); index++) {
            Object temp;
            if(mymap.containsKey(hexValue[index])){
                temp = mymap.get(hexValue[index]);
            }else{
                temp = hexValue[index];
            }
            result += Integer.valueOf(temp) * Integer.valueOf(Math.pow(16, base));
            base += 1;   
            
        }
        System.debug(result);
        return result;
        
    }
    
    public static Map<String,integer> convertCharintonum(){
        Map<String,Integer> mymap = new Map<String,Integer>();
        mymap.put('A',10);        
        mymap.put('B',11);
        mymap.put('C',12);
        mymap.put('D',13);
        mymap.put('E',14);
        mymap.put('F',15);
        mymap.put('a',10);
        mymap.put('b',11);
        mymap.put('c',12);
        mymap.put('d',13);
        mymap.put('e',14);
        mymap.put('f',15);
        return mymap;
        
    }
}

output :- World's simplest online text to hexadecimal