Java AsynchronousFileChannel read from file

import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousFileChannel;
import java.nio.charset.Charset;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.concurrent.Future;

public class Main {
  public static void main(String[] args) {
    Path path = Paths.get("Main.java");

    try (AsynchronousFileChannel afc = AsynchronousFileChannel.open(path,
        StandardOpenOption.READ)) {

      // Get a data buffer of the file size to read
      int fileSize = (int) afc.size();
      ByteBuffer dataBuffer = ByteBuffer.allocate(fileSize);

      // Perform the asynchronous read operation
      Future<Integer> result = afc.read(dataBuffer, 0);

      int readBytes = result.get();

      System.out.println(readBytes);

      byte[] byteData = dataBuffer.array();
      Charset cs = Charset.forName("UTF-8");
      String data = new String(byteData, cs);

      System.out.println(data);/*from w w w  .j a  va 2s.  c  o  m*/
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousFileChannel;
import java.nio.channels.CompletionHandler;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.EnumSet;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class Main {
   public static void main(String args[]) {
      ExecutorService pool = new ScheduledThreadPoolExecutor(3);
      try (AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(Paths.get("Main.java"),
            EnumSet.of(StandardOpenOption.READ), pool)) {
         System.out.println("Main Thread ID: " + Thread.currentThread().getId());

         CompletionHandler<Integer, ByteBuffer> handler = new CompletionHandler<Integer, ByteBuffer>() {

            @Override/*  w  w w  . ja  v  a 2s . c  om*/
            public synchronized void completed(Integer result, ByteBuffer attachment) {
               for (int i = 0; i < attachment.limit(); i++) {
                  System.out.print((char) attachment.get(i));
               }
               System.out.println("CompletionHandler Thread ID: " + Thread.currentThread().getId());
            }
            @Override
            public void failed(Throwable e, ByteBuffer attachment) {
               System.out.println("Failed");
            }
         };
         final int bufferCount = 5;
         ByteBuffer buffers[] = new ByteBuffer[bufferCount];
         for (int i = 0; i < bufferCount; i++) {
            buffers[i] = ByteBuffer.allocate(10);
            fileChannel.read(buffers[i], i * 10, buffers[i], handler);
         }
         pool.awaitTermination(1, TimeUnit.SECONDS);

         System.out.println("Byte Buffers");
         for (ByteBuffer byteBuffer : buffers) {
            for (int i = 0; i < byteBuffer.limit(); i++) {
               System.out.print((char) byteBuffer.get(i));
            }
            System.out.println();
         }
      } catch (IOException | InterruptedException ex) {
         ex.printStackTrace();
      }
   }
}