LinuxQuestions.org - how to transform an object into an array of bytes on Java!

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how to transform an object into an array of bytes on Java!

hello

I have an Object a and I wanna be able to save it's state on a random access file. I've learned that in order to write on a file I ne ed to transform it into a byte array. But how can I do it?

is there something like a.tobyteArray() ???

once that I've saved it, how can I retreive it for future use?

Thanks thanks thanks a lot!

Have you looked into the 'serializeable' interface? It might do what you want, it allows you to save objects and restore them later.

-Josh

This code does what you want... you should read the sun docs on the ObjectOutputStream object here: http://java.sun.com/j2se/1.4.1/docs/...putStream.html

Code:



import java.util.*;

import java.io.*;

                                                                                

public class ObjOut {

        public static void main(String[] args) throws Exception {

                                                                                

                // create some object

                ArrayList list = new ArrayList();

                list.add("One");

                list.add("Two");

                list.add("Three");

                                                                                

                ByteArrayOutputStream bos = new ByteArrayOutputStream();

                ObjectOutputStream out = new ObjectOutputStream(bos);

                out.writeObject(list);

                                                                                

                RandomAccessFile raf = new RandomAccessFile(

                        new File("./list"), "rw"

                );

                raf.write(bos.toByteArray());

                raf.close();

        }

}

Of course the code could be made more efficient by constructing the ObjectOutputStream with a FileOutputStream, instead of buffering the whole object in memory then writing it through the RandomAccessFile, but that's what you asked for.

HTH

B.

thanks a lot! that's exactly what I was looking for. Thanks!