'How to convert hex string to Java string?

For logging purpose we are converting the logs to byte array and then to hex string. I want to get it back in a Java String, but I am not able to do so.

The hex string in log file looks something like 

fd00000aa8660b5b010006acdc0100000101000100010000

How can I decode this?

javastringhex


Solution 1:[1]

Using Hex in Apache Commons:

String hexString = "fd00000aa8660b5b010006acdc0100000101000100010000";    
byte[] bytes = Hex.decodeHex(hexString.toCharArray());
System.out.println(new String(bytes, "UTF-8"));

Solution 2:[2]

byte[] bytes = javax.xml.bind.DatatypeConverter.parseHexBinary(hexString);
String result= new String(bytes, encoding);

Solution 3:[3]

You can go from String (hex) to byte array to String as UTF-8(?). Make sure your hex string does not have leading spaces and stuff.

public static byte[] hexStringToByteArray(String hex) {
    int l = hex.length();
    byte[] data = new byte[l / 2];
    for (int i = 0; i < l; i += 2) {
        data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
                + Character.digit(hex.charAt(i + 1), 16));
    }
    return data;
}

Usage:

String b = "0xfd00000aa8660b5b010006acdc0100000101000100010000";
byte[] bytes = hexStringToByteArray(b);
String st = new String(bytes, StandardCharsets.UTF_8);
System.out.println(st);

Solution 4:[4]

First of all read in the data, then convert it to byte array:

 byte b = Byte.parseByte(str, 16);

and then use String constructor:

new String(byte[] bytes)

or if the charset is not system default then:

new String(byte[] bytes, String charsetName)

Solution 5:[5]

Try the following code:

public static byte[] decode(String hex){

        String[] list=hex.split("(?<=\\G.{2})");
        ByteBuffer buffer= ByteBuffer.allocate(list.length);
        System.out.println(list.length);
        for(String str: list)
            buffer.put(Byte.parseByte(str,16));

        return buffer.array();

}

To convert to String just create a new String with the byte[] returned by the decode method.

Solution 6:[6]

Just another way to convert hex string to java string: 

public static String unHex(String arg) {        

    String str = "";
    for(int i=0;i<arg.length();i+=2)
    {
        String s = arg.substring(i, (i + 2));
        int decimal = Integer.parseInt(s, 16);
        str = str + (char) decimal;
    }       
    return str;
}

Solution 7:[7]

There is yet another way to do this if using JDK17 or above, see the new HexFormat class which has useful methods for converting byte[] <=> hexadecimal String :

String hexStr ="5468697320697320616e206578616d706c6520737472696e67";
byte[] bytes = HexFormat.of().parseHex(hexStr);
String str = new String(bytes, StandardCharsets.UTF_8 /* or Charset.forName("whateverencoding")*/);

You of course need to know the exact character encoding of the hexadecimal representation in order to generate the correct String value.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1
Solution 2
Solution 3 catch23
Solution 4
Solution 5 rink.attendant.6
Solution 6 Kunal Surana
Solution 7 DuncG

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