Java MappedByteBuffer write to file

import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.nio.file.InvalidPathException;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

public class Main {
   public static void main(String args[]) {
      try (FileChannel fChan = (FileChannel) Files.newByteChannel(Paths.get("test.txt"), StandardOpenOption.WRITE,
            StandardOpenOption.READ, StandardOpenOption.CREATE)) {
         MappedByteBuffer mBuf = fChan.map(FileChannel.MapMode.READ_WRITE, 0, 26);

         for (int i = 0; i < 26; i++){
            mBuf.put((byte) ('A' + i));
         }// w ww .  j  av a  2 s.c  o  m
      } catch (InvalidPathException e) {
         System.out.println("Path Error " + e);
      } catch (IOException e) {
         System.out.println("I/O Error " + e);
      }
   }
}