How to convert an Integer to byte[] without lose data?

I use the following to convert any java Object to a byte array
public static byte[] getBytes(Object obj) throws java.io.IOException
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bos);
        oos.writeObject(obj);
        oos.flush();
        oos.close();
        bos.close();
        byte [] data = bos.toByteArray();
        return data;
}

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How to convert a integer into bytes!!!

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!

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);
}

How to convert java class file version without decompiling

Hi,
Oracle R12.1.3 i am having illegal access error while try to access the class file version Java 1.3 uses major version 47,So how to convert the class file version without using decompiling.
Current java version is 1.6.0_07
Is there any tool or API for converting class file version?
Thanks,
Selvapandian T

Beside this I wonder where you get your error from since AFAIK 12c comes with java 1.6.
Well wonder no more!
OP isn't using Oracle 12c database.
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How to convert nagative integer to positive integer.

int i= (int)System.currentTimeMillis();
System.out.println(i);
The result is nagative
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Isn't it enough to multiply the integer with -1?!?
Or did � understand something wrong?
slaps head
Yes, but an int is only 32 bits wide; a long is 64
bits wide.
The fact that the int is negative isn't "real" - it's
because they cast it to the wrong type. System time
in millis is returned as a long, and that's what it
should be cast to.
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How to convert an integer to a sting in an expression

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Rafi

Hi Rafi,
Step.Result.ReportText = "This is channel No. " + Str(Local.ChNo)
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Regards
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import javax.swing.*;
import java.awt.*;
public class Hw extends JFrame{
     JButton[] buttons = new JButton[26];
     public Hw(){
          getContentPane().setLayout(new GridLayout(2,13));
          JButton []buttons=new JButton[26];
          for(int i=65; i<90;i++)
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I have 26 buttons and each buttons will contain a character like A,B,C,D,...
but i dont know how to convert it from integer to string

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import java.awt.*;
public class Hw extends JFrame{
     JButton[] buttons = new JButton[26];
     public Hw(){
          getContentPane().setLayout(new GridLayout(2,13));
          JButton []buttons=new JButton[26];
          for(int i=0; i<buttons.length;i++)
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tjacobs01 , thnx for urgent reply, but i didnt apply your algorithm inside of the my program, if its possible can u compile the program with your codes..
its a little complex for me i didnt understand anythind :S

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Integer y = new Integer(1);
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It's mid nite and I'm still at work!
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String blah = Keyboard.readLine();
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newer copy

How to convert an Object to byte[]

How do I convert an object to a byte array without using the ObjectOutputStream?
I need to send an object over UDP socket which only works with byte[].

instead of serialisation for complex object i usexm and sax to transfer information over the network,
it works great
works nothing when transfering over the ORBWhen programming with a socket, sendTo is a standard function used in the connectionless protocol. I rewrote this function so as to be able to transmit objects. The following code example shows how to implement the send method in a Sender class:
import java.io.*;
import java.net.*;
public class Sender
{ public void sendTo(Object o, String hostName, int desPort)
{    try
{      InetAddress address = InetAddress.getByName(hostName);
ByteArrayOutputStream byteStream = new
ByteArrayOutputStream(5000);
ObjectOutputStream os = new ObjectOutputStream(new
BufferedOutputStream(byteStream));
os.flush();
os.writeObject(o);
os.flush();
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byte[] sendBuf = byteStream.toByteArray();
DatagramPacket packet = new DatagramPacket(
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int byteCount = packet.getLength();
dSock.send(packet);
os.close();
catch (UnknownHostException e)
System.err.println("Exception: " + e);
e.printStackTrace(); }
catch (IOException e) { e.printStackTrace();
The code listing below demonstrates how to implement a receive method in a Receiver class. Method recvObjFrom is for the receiver to receive the object. You can include this method in your code to receive runtime objects.
import java.io.*;
import java.net.*;
public class Receiver
{ public Object recvObjFrom()
{    try
byte[] recvBuf = new byte[5000];
DatagramPacket packet = new DatagramPacket(recvBuf,
recvBuf.length);
dSock.receive(packet);
int byteCount = packet.getLength();
ByteArrayInputStream byteStream = new
ByteArrayInputStream(recvBuf);
ObjectInputStream is = new
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Object o = is.readObject();
is.close();
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catch (IOException e)
System.err.println("Exception: " + e);
e.printStackTrace();
catch (ClassNotFoundException e)
{ e.printStackTrace(); }
return(null); }
One may worry about the size of the byte array -- because when you construct ByteArrayOutputStream or ByteArrayInputStream, you have to specify the size of the array. Since you don't know the size of a runtime object, you will have trouble specifying that size. The size of a runtime object is often unpredictable. Fortunately, Java's ByteArrayInputStream and ByteArrayOutputStream classes can extend their sizes automatically whenever needed.
By
Sree Visveswaran

How to convert an Integer to byte[] without lose data?

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