Re: Size of an arraylist in bytes

sara <>
Sun, 20 Nov 2011 13:11:00 -0800 (PST)
Here is the code:

        ArrayList<Integer> tmp=new ArrayList<Integer>();
        tmp.set(0, 10);

    public static byte[] GetBytes(Object v) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos;
        try {
            oos = new ObjectOutputStream(bos);
        } catch (IOException e) {
        byte[] data = bos.toByteArray();
        return data;

The problem is I need to write multiple arraylists on disk and later
on I update the elements of them. I store the starting location of
arraylists and their size such that later I can refer to them. If the
size of objects change then it messes up! Could you please help?
On Nov 20, 1:05 pm, markspace <-@.> wrote:

On 11/20/2011 1:01 PM, sara wrote:

Hi All,

I create an Arraylist<Integer> tmp and add some integers to it.
Afterward, I measure the size of tmp in bytes (by converting tmp to
bytes array). Assume the result is byte[] C. However, when I update an
element of tmp, and measure size of tmp in bytes again, the result is
different than C!
Why this is the case?

We'd have to see some code to give you a good answer, but basically you
can't measure the memory size of Java objects. They change over time,
in ways that C or C++ can't or doesn't, and there's not much to do that
can rectify that.

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