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Getting bytes from the bytes array

Posted on 2006-10-21
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Last Modified: 2010-03-31
Hi Friends,
I receive data from the server and I store it in a bytes array.Now I need to retrieve bytes from the array,like first byte says code[1 byte],second says lastname[4 bytes],third says fname[30 bytes],last byte says if there is one more entry,and the same syntax needs to be followed again....I tried this but its not working...any help would be appreciated.


import java.io.*;
import java.nio.*;
 
public class btest{
public static void main(String[] ar){
 try{
 
                String data1 ="1232 3 3 444 222 111 444 555555 2222222 1111111 3333 dssssddd";
                byte[] data = data1.getBytes("ASCII");
            int length = data.length;
            System.out.println("length is:"+length);
            ByteBuffer buff = ByteBuffer.wrap(data);
 
            byte[] fbyte = new byte[1];
            byte[] lname = new byte[4];
            byte[] fname = new byte[30];
            byte[] lbyte = new byte[1];
            
            buff.get(fbyte, 0,1);
            String received0 = new String(fbyte,"ASCII");
                System.out.println("Data Recd: " + received0);
            buff.position(1);
            
            buff.get(ref_no, 1,4);            
            String received1 = new String(lname,"ASCII");
            buff.position(4);
 
            buff.get(uname, 4,34);
              String received2 = new String(fname,"ASCII");
                System.out.println("Data Recd: " + received2);
            buff.position(34);
 
            buff.get(lbyte, 34,35);
            String received3 = new String(lbyte,"ASCII");
                System.out.println("Data Recd: " + received3);
 
}catch(Exception e){e.printStackTrace();}
 
}
}

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Question by:harmeek_80
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5 Comments
 
LVL 86

Expert Comment

by:CEHJ
ID: 17782874
You don't need to move anything or calculation positions - the BB will do that for you

buff.get(fbyte);
String received0 = new String(fbyte,"ASCII");
System.out.println("Data Recd: " + received0);

buff.get(ref_no);


etc.
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LVL 92

Expert Comment

by:objects
ID: 17782939
>           buff.get(ref_no, 1,4);          

your problem is that those values refer to where in ref_no to place the bytes :)

What you want can also easily be done without even needing to create a ByteBuffer, and use Syste.arraycopy to copy the bytes directly from the byte array
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LVL 86

Assisted Solution

by:CEHJ
CEHJ earned 50 total points
ID: 17782950
It's actually easier to do it with a BB - it's been designed especially for this sort of thing
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LVL 92

Accepted Solution

by:
objects earned 100 total points
ID: 17782969
you also need to remove those calls to position (they are relative gets) and do it in a loop
there are a variety of other minor prob also with the code
try something like:

boolean done = false;
while (!done) {
          buff.get(fbyte);
          String received0 = new String(fbyte,"ASCII");
          System.out.println("Data Recd: " + received0);
         
          buff.get(fname);
          String received1 = new String(fname,"ASCII");
          System.out.println("Data Recd: " + recieved1);
 
          buff.get(lname);
          String received2 = new String(lname,"ASCII");
          System.out.println("Data Recd: " + recieved2);

          buff.get(lbyte);
          String received3 = new String(lbyte,"ASCII");
          System.out.println("Data Recd: " + received3);
          done = !recieved3.equals(MORE_DATA);
}
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LVL 86

Expert Comment

by:CEHJ
ID: 17784478
Not sure how that answer added anything to the one i'd already given, although it did repeat it
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