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

From:
markspace <nospam@nowhere.com>
Newsgroups:
comp.lang.java.help
Date:
Fri, 25 Sep 2009 14:59:15 -0700
Message-ID:
<h9jefm$der$1@news.eternal-september.org>
Alexandre Ferrieux wrote:

How do we accomplish this simple task of a direct write to disk of a
big (packed) array of ints, in native byte order ?


What Patricia said. Tested, but not profiled or anything:

package fubar;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import java.nio.channels.FileChannel;

public class DirectWrite {

     private static final int CAP = 8*1024;

     private static final int[] testArray =
         { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };

     public static void main( String[] args ) throws
FileNotFoundException, IOException
     {
         File f = new File("test.test");
         FileOutputStream fos = new FileOutputStream( f );
         ByteBuffer bb = ByteBuffer.allocateDirect( CAP );
         IntBuffer ib = bb.asIntBuffer();
         ib.put( testArray );
         FileChannel fc = fos.getChannel();
         fc.write( bb );
         fc.close();
         // tidy up
         f.delete();
     }

}

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