Java Hex Convert To fromHexString(String input)

Description

from Hex String

License

Apache License

Declaration

public static byte[] fromHexString(String input) 

Method Source Code

//package com.java2s;
/*/* w ww.jav  a2  s  . c om*/
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

public class Main {
    /**
     *  Table for HEX to DEC byte translation.
     */
    private static final int[] DEC = { 00, 01, 02, 03, 04, 05, 06, 07, 8,
            9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, };

    public static byte[] fromHexString(String input) {
        if (input == null) {
            return null;
        }

        if ((input.length() & 1) == 1) {
            // Odd number of characters
            throw new IllegalArgumentException(
                    "The input must consist of an even number of hex digits");
        }

        char[] inputChars = input.toCharArray();
        byte[] result = new byte[input.length() >> 1];
        for (int i = 0; i < result.length; i++) {
            int upperNibble = getDec(inputChars[2 * i]);
            int lowerNibble = getDec(inputChars[2 * i + 1]);
            if (upperNibble < 0 || lowerNibble < 0) {
                // Non hex character
                throw new IllegalArgumentException(
                        "The input must consist only of hex digits");
            }
            result[i] = (byte) ((upperNibble << 4) + lowerNibble);
        }
        return result;
    }

    public static int getDec(int index) {
        // Fast for correct values, slower for incorrect ones
        try {
            return DEC[index - '0'];
        } catch (ArrayIndexOutOfBoundsException ex) {
            return -1;
        }
    }
}

Related

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