Re: How to (efficiently) write an int array into a file ?

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.help
Date:
Sat, 26 Sep 2009 12:53:12 -0400
Message-ID:
<h9lgto$6ue$2@news.albasani.net>
Lew wrote:

Roedy Green wrote:

On Sat, 26 Sep 2009 11:47:19 -0400, Lew <noone@lewscanon.com> wrote,
quoted or indirectly quoted someone who said :

As for your conclusions about speed, on what evidence are they based?


C writes a block of ints as a large chunk of bytes. It does not need
to do any processing on each element the way Java does with
DataOutputStream.

Here is the code for DataOutputStream.writeInt()

 /**
     * Writes an <code>int</code> to the underlying output stream as
four
     * bytes, high byte first. If no exception is thrown, the counter
     * <code>written</code> is incremented by <code>4</code>.
     *
     * @param v an <code>int</code> to be written.
     * @exception IOException if an I/O error occurs.
     * @see java.io.FilterOutputStream#out
     */
    public final void writeInt(int v) throws IOException {
        out.write((v >>> 24) & 0xFF);
        out.write((v >>> 16) & 0xFF);
        out.write((v >>> 8) & 0xFF);
        out.write((v >>> 0) & 0xFF);
        incCount(4);
    }

I think Lew may have expected writeInt to be a native method that
copied 4 bytes as a single chunk to the output buffer.


I think Lew may have been speaking about the NIO buffer approach.


or the write(byte[] b) approach.

I mean, come on - duhhh.

--
Lew

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