Problem outputting to the screen using FileDescriptor.out

Question

I have the following program that reads prime numbers from a binary file. The issue is that the numbers are not printing to the screen using
FormatWriter out = new FormatWriter(
       new BufferedWriter(
       new FileWriter(FileDescriptor.out)));The numbers are being read from the file as if I unblock the line
// System.out.println(primes[j]); the numbers are printed to the screen.
I have pasted the code below and the code that creates the prime numbers file.
Thanks for any help.
package readprimes;
import java.io.*;
public class ReadPrimes {
   public static void main(String[] args) {
       File myPrimes;
       DataInputStream primesIn;
        try{
            String directory = "C:/JunkData";
            String fileName = "Prime.bin";
            myPrimes = new File(directory, fileName);
             primesIn = new DataInputStream(new FileInputStream(myPrimes));
        catch(FileNotFoundException e){
            return;
        catch(IOException e){
            return;
    FormatWriter out = new FormatWriter(
       new BufferedWriter(
       new FileWriter(FileDescriptor.out)));
        long[] primes = new long[6];
        boolean EOF = false;
        while(!EOF){
            int index = 0;
            try{
                for(index = 0; index < primes.length; index++)
                    primes[index] = primesIn.readLong();
                   catch(IOException e){
            return;
//             catch(EOFException e){
//                 EOF =  true;
            for(int j = 0;j < index; j++){
         //       System.out.println(primes[j]);
                out.print(primes[j]);
                out.println();
out.close();
package readprimes;
import java.io.PrintWriter;
import java.io.*;
public class FormatWriter extends PrintWriter{
    private int width = 10;
    public FormatWriter(Writer output){
        super(output);
    public FormatWriter(Writer output, int width){
        super(output);
        this.width = width;
    public FormatWriter(Writer output, boolean autoflush){
        super(output, autoflush);
        public FormatWriter(Writer output, boolean autoflush, int width){
        super(output, autoflush);
        this.width = width;
Class that creates the prime number file
package bufferedoutput;
import java.io.*;
public class TryPrimesOutput {
   public static void main(String[] args) {
       long[] primes = new long[200];
       primes[0] = 2;
       primes[1] = 3;
       int count = 2;
       long number = 5;
       outer:
       for(; count < primes.length; number +=2L)
           long limit = (long)Math.ceil(Math.sqrt((double)number));
           for(int i = 1; i <count && primes<= limit; i++)
if(number%primes[i]==0)
continue outer;
primes[count++] = number;
try
String dirName = "c:\\JunkData";
String fileName = "Prime.bin";
File myPrimeDir = new File(dirName);
if(!myPrimeDir.exists())
myPrimeDir.mkdir();
else
if(!myPrimeDir.isDirectory())
System.err.println();
return;
File primesFile = new File(myPrimeDir, fileName);
primesFile.createNewFile();
DataOutputStream primesStream = new DataOutputStream(
new BufferedOutputStream(
new FileOutputStream(primesFile)));
for(int i = 0; i <primes.length;i++)
primesStream.writeLong(primes[i]);
primesStream.close();
catch(IOException e){
System.out.println("IOExcetoptj");

Answer 1

Indeed. It isn't obvious to me what the result of new FileWriter(FileDescriptor.out) would result in, but your test appears to show that it doesn't result in something which can be used to output to the console.