//OpenFileDemo.java

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class OpenFileDemo
{
    public static void main(String[] args)
    {
        System.out.println("Enter file name:");
        Scanner keyboard = new Scanner(System.in);
        String fileName = keyboard.next();

        PrintWriter outputStream = null;
        try
        {
            outputStream = openOutputTextFile(fileName);
        }
        catch (FileNotFoundException e)
        {
            System.out.println("Error opening the file " + fileName);
            System.exit(0);
        }

        System.out.println("Enter nonnegative integers.");
        System.out.println("Place a negative number at the end.");
        keyboard = new Scanner(System.in);

        int integer;
        do
        {
            integer = keyboard.nextInt();
            outputStream.println(integer);
        }
        while (integer >= 0);

        System.out.print("Numbers and sentinel value ");
        System.out.println("written to the file.");
        outputStream.close();
    }

    public static PrintWriter openOutputTextFile
    (
        String fileName
    ) throws FileNotFoundException
    {
        PrintWriter toFile = new PrintWriter(fileName);
        return toFile;
    }
}