Hi,Everyone:
Here is my solotion to change from int  to byte[] ,is there a better
solution ?

import java.util.*;
import java.io.*;
import java.lang.*;
import javax.sql.rowset.serial.*;
public class Indexes {

    public int hashCode;
    public String hashString;
    public SerialBlob blob;
    public byte[] b;
    public int length;
    public int numberOfIDs;
    public int capability;
    public  ArrayList intArray;
    public int lastid; // to make note of last insert ID of intArray
    public void DoubleSize()
    {
        byte temp[] = new byte[capability*2];
        for(int i = 0 ; i< length; i++)
        {
            temp[i] = b[i];
        }
        b = temp;
    }
    public void AddToBytes(int x)
    {
        int temp = x;
        for( int i = 0 ;i<=3 ; i++ ){
       b[length++] =  new Integer(x & 0xFF).byteValue();
        temp = temp >> 8;
        }

    }
    public void IntToByte ()
    {
        b = new byte [intArray.size()*5+20];
        length = 0;
        this.capability = intArray.size()*5+20;
        for(int i = 0 ;i<intArray.size() ;i++)
        {
            if (this.capability -5 < length ) { DoubleSize();}
            Index temp = (Index)intArray.get(i);
            AddToBytes(temp.fileid);
            b[length++] = temp.pos ;
        }
    }
}