FileChannel Buffer LECTURE

Bonjour, dans la cadre d'exercices sur les Buffer, je teste le programmme suivant trouvé dans la JAVADOCEXAMPLES

Le problème est que "il propose l'écriture du fichier mais pas la lecture"

C'est malheureusement la lecture que je ne parviens pas à maîtriser

Voici la tentative de code (AJOUT en vert dans la bas ) pour la lecture

Pouvez-vous me donner quelques suggestions, Merci
Code:
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package tampons_jeter;

import static java.lang.Math.ceil;  
import static java.lang.Math.sqrt;  
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.nio.ByteBuffer;
import java.nio.LongBuffer;
import java.nio.DoubleBuffer;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;

import javax.imageio.stream.FileImageInputStream;
 
	  public class PrimesToFile2 {
	    public static void main(String[] args) throws IOException {
    int primesRequired = 100;   // Default count
	      if (args.length > 0) {
	        try {
        primesRequired = Integer.valueOf(args[0]).intValue();
      } catch (NumberFormatException e) {
        System.out.println("Prime count value invalid. Using default of "
                           + primesRequired);
      } 
    } 

    long[] primes = new long[primesRequired];    // Array to store primes
    primes[0] = 2;                               // Seed the first prime
    primes[1] = 3;                               // and the second
    int count = 2;                               // Count of primes found - up to now, which is also the array index
    long number = 5;                             // Next integer to be tested

    outer:
	      for (; count < primesRequired; number += 2) {

      // The maximum divisor we need to try is square root of number
      long limit = (long)ceil(sqrt((double)number));

      // Divide by all the primes we have up to limit
      for (int i = 1; i < count && primes[i] <= limit; i++) 
        if (number % primes[i] == 0)             // Is it an exact divisor?
          continue outer;                        // yes, try the next number

      primes[count++] = number;                  // We got one!
    }

    File aFile = new File("primes.txt");
    FileOutputStream outputFile = null;
	      try {
      outputFile = new FileOutputStream(aFile);
    } catch (FileNotFoundException e) {
      e.printStackTrace(System.err);
      System.exit(1);
    } 
    FileChannel file = outputFile.getChannel();
    final int BUFFERSIZE = 100;                  // Buffer size in bytes
    ByteBuffer buf = ByteBuffer.allocate(BUFFERSIZE);

    DoubleBuffer doubleBuf = buf.asDoubleBuffer();
    buf.position(8);
    CharBuffer charBuf = buf.asCharBuffer();
    LongBuffer longBuf = null;
    String primeStr = null;

	      for (long prime : primes) {
      primeStr = "prime = " + prime;             // Create the string
      doubleBuf.put(0,(double)primeStr.length()); // Store the string length
      charBuf.put(primeStr);                     // Store the string
      buf.position(2*charBuf.position() + 8);    // Position for 3rd buffer
      longBuf = buf.asLongBuffer();              // Create the buffer
      longBuf.put(prime);                        // Store the binary long value
      buf.position(buf.position() + 8);          // Set position after last value
      buf.flip();                                // and flip
	        try {
        file.write(buf);                         // Write the buffer as before.
        
                
      } catch (IOException e) {
        e.printStackTrace(System.err);
        System.exit(1);
      } 
      buf.clear();
      doubleBuf.clear();
      charBuf.clear();
    } 
	      try {
      System.out.println("File written is " + file.size() + " bytes.");
      outputFile.close();                        // Close the file and its channel
    } catch (IOException e) {
      e.printStackTrace(System.err);
      System.exit(1);
    }
    
    //AJOUT pour lire mais NOT OK
    
    System.out.println();
    System.out.println("Essai lecture ");
    File aFile2 = new File("primes.txt");
    
    FileInputStream inputFile =  new FileInputStream(aFile2);
    FileChannel fci = inputFile.getChannel();
    
    buf.position(8);
    buf.limit(35);
    //for (long prime : primes) {
    int nb = 0;
    while ((nb = fci.read(buf)) != -1){
    	//fci.read(buf);
        System.out.println(doubleBuf.get(0));
        System.out.println(charBuf.get());
        buf.position(2*charBuf.position() + 8);
        System.out.println(longBuf.get());
        buf.position(buf.position() + 8);
        buf.flip();
        
    }
    
    
    System.exit(0);
  }
}