Example 1: Convert Byte Array to Hex value

public class ByteHex{

    public static void main(String[] args){

        byte[] bytes = {10, 2, 15, 11};

        for (byte b : bytes) {
            String st = String.format("%02X", b);
            System.out.print(st);
        }
    }
}

Output

0A020F0B

In the above program, we have a byte array named bytes. To convert byte array to a hex value, we loop through each byte in the array and use String‘s format().

We use %02X to print two places (02) of Hexadecimal (X) value and store it in the string st.

This is a relatively slower process for large byte array conversion. We can dramatically increase the speed of execution using byte operations shown below.

Example 2: Convert Byte Array to Hex value using byte operations

public class ByteHex{

    private final static char[] hexArray = "0123456789ABCDEF".toCharArray();
    public static String bytesToHex(byte[] bytes){
        char[] hexChars = new char[bytes.length * 2];
        for ( int j = 0; j < bytes.length; j++ ) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }
        return new String(hexChars);
    }

    public static void main(String[] args){

        byte[] bytes = {10, 2, 15, 11};

        String s = bytesToHex(bytes);
        System.out.println(s);

    }
}

The output of the program is the same as Example 1.