encode Hex : Hash Code « Development Class « Java

encode Hex

 * @(#)$Id: StringUtils.java 3619 2008-03-26 07:23:03Z yui $
 * Copyright 2006-2008 Makoto YUI
 * Licensed 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * Contributors:
 *     Makoto YUI - initial implementation
//package xbird.util.string;

 * <DIV lang="en"></DIV>
 * <DIV lang="ja"></DIV>
 * @author Makoto YUI (yuin405+xbird@gmail.com)
public final class StringUtils {

    private static final char[] HEX_DIGITS = "0123456789ABCDEF".toCharArray();
    private static final int UPPER_NIBBLE_MASK = 0xF0;
    private static final int LOWER_NIBBLE_MASK = 0x0F;

    public static void encodeHex(final byte b, final StringBuilder buf) {
        final int upper = (b & UPPER_NIBBLE_MASK) >> 4;
        final int lower = b & LOWER_NIBBLE_MASK;

    public static String encodeHex(final byte[] buf) {
        final int buflen = buf.length;
        final char[] ch = new char[buflen * 2];
        for(int i = 0, j = 0; i < buf.length; i++, j += 2) {
            final byte b = buf[i];
            final int upper = (b & UPPER_NIBBLE_MASK) >> 4;
            final int lower = b & LOWER_NIBBLE_MASK;
            ch[j] = HEX_DIGITS[upper];
            ch[j + 1] = HEX_DIGITS[lower];
        return new String(ch);

    public static byte[] decodeHex(final char[] data) {
        final int len = data.length;
        if((len & 0x01) != 0) {
            throw new IllegalArgumentException("Illegal HexaDecimal character");
        final byte[] out = new byte[len >> 1];
        for(int i = 0, j = 0; j < len; i++) {
            int f = hexToDigit(data[j], j) << 4;
            f = f | hexToDigit(data[j], j);
            out[i] = (byte) (f & 0xFF);
        return out;

    private static int hexToDigit(final char ch, final int index) {
        final int digit = Character.digit(ch, 16);
        if(digit == -1) {
            throw new IllegalArgumentException("Illegal HexaDecimal character '" + ch
                    + "' at index " + index);
        return digit;



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