Java Hex Convert To fromHexString(String hexString)

Description

Converts the hex-string back into an array of bytes

License

Open Source License

Parameter

Parameter	Description
hexString	Hex string, such as "0123456789ABCDEF", where each byte is represented by two characters

Return

Byte representation of the hex string, will be half the length of string

Declaration

public static byte[] fromHexString(String hexString) 

Method Source Code

//package com.java2s;
/*/*from ww w. j  a  v  a 2 s.  c  o m*/
 * File:                HashFunctionUtil.java
 * Authors:             Kevin R. Dixon
 * Company:             Sandia National Laboratories
 * Project:             Cognitive Foundry
 *
 * Copyright Jan 26, 2011, Sandia Corporation.
 * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
 * license for use of this work by or on behalf of the U.S. Government.
 * Export of this program may require a license from the United States
 * Government. See CopyrightHistory.txt for complete details.
 *
 */

public class Main {
    /**
     * Char table for convenience
     */
    static final char[] HEX_CHAR_TABLE = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
            'e', 'f' };

    /**
     * Converts the hex-string back into an array of bytes
     * @param hexString
     * Hex string, such as "0123456789ABCDEF", where each byte is represented
     * by two characters
     * @return
     * Byte representation of the hex string, will be half the length of string
     */
    public static byte[] fromHexString(String hexString) {

        // It takes two chars to represent a single byte
        final int sl = hexString.length();
        if ((sl % 2) != 0) {
            throw new IllegalArgumentException("hexString must be even length");
        }

        byte[] bytes = new byte[sl / 2];
        for (int i = 0; i < sl; i += 2) {
            final int j = i / 2;
            byte high = valueOf(hexString.charAt(i));
            byte low = valueOf(hexString.charAt(i + 1));
            byte value = (byte) (((high & 0xf) << 4) | (low & 0xf));
            bytes[j] = value;
        }

        return bytes;

    }

    /**
     * Returns the hex value of the given character
     * @param hexChar
     * Hex character, such as '0' or 'A'
     * @return
     * The value of the hex character.
     */
    public static byte valueOf(char hexChar) {
        hexChar = Character.toLowerCase(hexChar);
        for (byte i = 0; i < HEX_CHAR_TABLE.length; i++) {
            if (hexChar == HEX_CHAR_TABLE[i]) {
                return i;
            }
        }
        throw new IllegalArgumentException(hexChar + " is not a hex char");
    }
}

Related

1. fromHexString(String encoded)
2. fromHexString(String hex)
3. fromHexString(String hex)
4. fromHexString(String hexString)
5. fromHexString(String hexString)
6. fromHexString(String hexString)
7. fromHexString(String in)
8. fromHexString(String input)
9. fromHexString(String input)