StringUtils.java Source code

Introduction

Here is the source code for StringUtils.java

Source

/*
 * @(#)$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,
 * 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.
 * 
 * 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;
        buf.append(HEX_DIGITS[upper]);
        buf.append(HEX_DIGITS[lower]);
    }

    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;
            j++;
            f = f | hexToDigit(data[j], 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;
    }

}