How to convert a integer into bytes!!!

Question

I am trying to pack the length of the data transamitted over a stream into 2 bytes (Each byte is a unsigned char in terms of 'C' language). When i am using the bytes in java any value greater than 127 is a negative number (I understand the very definition of 'byte' in java), my question is how to pack the length of the data the 'C' way still following Java rules??
Example :: Length of the data is 168 say!
the 2 bytes would be 0x00, 0x80 (the respective ascii values would be NULL, P) but with Java i get some thing different as we know??
byte 1 = 00 and byte 2 = -88 ( i am not sure what would be the ascii equivalent of this??)
Please help!

Answer 1

For what it's worth:package ca.adaptor.util;
* $Id: ByteUtil.java,v 1.6 2003/03/28 18:24:47 mike Exp $
* Copyright (c) 2002 by Michael Coury
*  This library is free software; you can redistribute it and/or
*  modify it under the terms of the GNU Lesser General Public
*  License as published by the Free Software Foundation; either
*  version 2.1 of the License, or (at your option) any later version.
*  This library is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
*  Lesser General Public License for more details.
*  You should have received a copy of the GNU Lesser General Public
*  License along with this library; if not, write to the Free Software
*  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
* @author Michael Coury (mdc)
* @created Sep 20, 2002
* @version $Revision: 1.6 $, $Date: 2003/03/28 18:24:47 $
public final class ByteUtil {
  private static final int  __NUM_BYTES_IN_LONG_   = 8;
  private static final int  __NUM_BYTES_IN_INT_    = 4;
  private static final int  __NUM_BYTES_IN_SHORT_  = 2;
  private static final int  __NUM_BITS_IN_BYTE_    = 8;
  private static final long __BYTE_MASK_           = 0xFF;
  /** PRIVATE CONSTRUCTOR */
  private ByteUtil() {}
            ///// ENCODE /////
   * Converts a number to its binary equivalent and returns that as a byte array
  public static final byte[] toBytes(final long aNum) {
    final byte[] ret = new byte[__NUM_BYTES_IN_LONG_];
    for(int i = 0; i < __NUM_BYTES_IN_LONG_; i++)
      ret[i] = (byte) (aNum >>> ((__NUM_BYTES_IN_LONG_ - 1 - i) * __NUM_BITS_IN_BYTE_));
    return ret;
   * Converts a number to its binary equivalent and returns that as a byte array
  public static final byte[] toBytes(final int aNum) {
    final byte[] ret = new byte[__NUM_BYTES_IN_INT_];
    for(int i = 0; i < __NUM_BYTES_IN_INT_; i++)
      ret[i] = (byte) (aNum >>> ((__NUM_BYTES_IN_INT_ - 1 - i) * __NUM_BITS_IN_BYTE_));
    return ret;
   * Converts a number to its binary equivalent and returns that as a byte array
  public static final byte[] toBytes(final short aNum) {
    final byte[] ret = new byte[__NUM_BYTES_IN_SHORT_];
    for(int i = 0; i < __NUM_BYTES_IN_SHORT_; i++)
      ret[i] = (byte) (aNum >>> ((__NUM_BYTES_IN_SHORT_ - 1 - i) * __NUM_BITS_IN_BYTE_));
    return ret;
   * Converts a number to its binary equivalent and returns that as a byte array
  public static final byte[] toBytes(final double aNum) {
    return toBytes(Double.doubleToRawLongBits(aNum));
   * Converts a number to its binary equivalent and returns that as a byte array
  public static final byte[] toBytes(final float aNum) {
    return toBytes(Float.floatToRawIntBits(aNum));
            ///// DECODE /////
   * Converts a byte array representing a long back to a long
  public static final long toLong(final byte[] aNum) {
    try {
      long ret = 0L;
      for(int i = 0; i < __NUM_BYTES_IN_LONG_; i++) {
        ret += ((long) aNum[i] & __BYTE_MASK_) << ((__NUM_BYTES_IN_LONG_ - 1 - i) * __NUM_BITS_IN_BYTE_);
      return ret;
    catch(Exception e) {
      throw new NumberFormatException("Invalid number of bytes for long.  Found: " + aNum.length
                                      + " Required: " + __NUM_BYTES_IN_LONG_);
   * Converts a byte array representing an int back to an int
  public static final int toInt(final byte[] aNum) {
    try {
      int ret = 0;
      for(int i = 0; i < __NUM_BYTES_IN_INT_; i++)
        ret += (aNum[i] & __BYTE_MASK_) << ((__NUM_BYTES_IN_INT_ - 1 - i) * __NUM_BITS_IN_BYTE_);
      return ret;
    catch(Exception e) {
      throw new NumberFormatException("Invalid number of bytes for int.  Found: " + aNum.length
                                      + " Required: " + __NUM_BYTES_IN_INT_);
   * Converts a byte array representing a short back to a short
  public static final short toShort(final byte[] aNum) {
    try {
      short ret = 0;
      for(int i = 0; i < __NUM_BYTES_IN_SHORT_; i++)
        ret += (aNum[i] & __BYTE_MASK_) << ((__NUM_BYTES_IN_SHORT_ - 1 - i) * __NUM_BITS_IN_BYTE_);
      return ret;
    catch(Exception e) {
      throw new NumberFormatException("Invalid number of bytes for short.  Found: " + aNum.length
                                      + " Required: " + __NUM_BYTES_IN_SHORT_);
   * Converts a byte array representing a double back to a double
  public static final double toDouble(final byte[] aNum) {
    return Double.longBitsToDouble(toLong(aNum));
   * Converts a byte array representing a float back to a float
  public static final float toFloat(final byte[] aNum) {
    return Float.intBitsToFloat(toInt(aNum));
            ///// SHIFTING /////
  public static final byte shiftRightUnsigned(final byte b, final int shift) {
    return (shift > __NUM_BITS_IN_BYTE_) ? 0x00 : (byte) ((b & 0xFF) >>> shift);
  public static final byte shiftRight(final byte b, final int shift) {
    return (byte) (b >> shift);
  public static final byte shiftLeft(final byte b, final int shift) {
    return (shift > __NUM_BITS_IN_BYTE_) ? 0x00 : (byte) (b << shift);
}