import java.io.*;

public class BinaryOutputDemo
{
   public static void main(String[] args)
   {
      try
      {
         ObjectOutputStream outputStream =
             new ObjectOutputStream(new FileOutputStream("numbers.dat"));
         int n;

         System.out.println("Enter nonnegative integers, one per line.");
         System.out.println("Place a negative number at the end.");

         do
         {
            n = SavitchIn.readLineInt( );
            outputStream.writeInt(n);
         }while (n >= 0);
        
         System.out.println("Numbers and sentinel value");
         System.out.println("written to the file numbers.dat.");
         outputStream.close( );
      }
      catch(IOException e)
      {
         System.out.println("Problem with output to file numbers.dat.");
      }
   }
}