How to read different objects from byte[]

Question

I have a byte[] with 3 different objects. How can I read from the byte[] and separate the objects?

My code:

  public byte[] toByteArray() {

            byte[] bytes;
            byte[] sb = start.toString().getBytes();
            byte[] gb = goal.toString().getBytes();
            byte[] mb = gameBoard.toString().getBytes();
            bytes = new byte[sb.length + gb.length + mb.length];
            System.arraycopy(sb, 0, bytes, 0, sb.length);
            System.arraycopy(gb, 0, bytes, sb.length, gb.length);
            System.arraycopy(mb, 0, bytes, gb.length, mb.length);
            return bytes;

        }

It seams java code. Additionally your code doesn't save objects but only the string representation of an object that is very different from the object itself, so if your class gameBoard redefine the toString() method to return "HELLO" your bytes will be filled with H E L L O, that is nothing to do with the gameBoard — Davide Lorenzo MARINO, Sep 01 '15 at 09:55

score 3 · Answer 1 · edited May 23 '17 at 12:16

3

Seems like you are talking about Java not JavaScript.

I recommend you to have a look at binary serialization which I guess is what you are looking for: Saving to binary/serialization java

edited May 23 '17 at 12:16

Community

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answered Sep 01 '15 at 09:56

Timo Denk

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score 2 · Answer 2 · answered Sep 01 '15 at 10:02

If you store your data like this, it will be a very difficult task to read them.

I recommend using some build-in object-to-byte[] (and back) conversions like Serializable.

Also, to store several object inside one byte[] array, have a look into ObjectOutputStream

Javier · Answer 3 · 2015-09-01T10:25:22.483

First of all you will need an actual byte[] where stuff can be read from. There are some issues about what you are trying.

toString() usually is not fit to get some data you can reconstruct the object from. It might work with an integer, get a bit messed up with floating point, and be outright impossible with complex objects which only tell about their type and id. (as Davide comment pointed)
There are no cues about where one object starts and ends. Even worse: you might have messed up the start position of 3rd object.

The JRE has a built-in serialization. Other people use XML or JSON when they need to interact with something else. You might even implement your own flavor of java.text.Format which is able to format and parse your objects. Pick your poison.

How to read different objects from byte[]

3 Answers3