import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.File;
import java.io.PrintWriter;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
 
public class FileClassDemo
{
    public static void main(String[] args)
    {
        BufferedReader keyboard = new BufferedReader(
                                   new InputStreamReader(System.in));
        String line = null;
        String fileName = null;
 
        try
        { 
            System.out.println("I will store a line of text for you.");
            System.out.println("Enter the line of text:");
            line = keyboard.readLine( );
 
            System.out.println("Enter a file name to hold the line:");
            fileName = keyboard.readLine( );
            fileName = fileName.trim( );
            File fileObject = new File(fileName);
            while (fileObject.exists( ))
            {
                System.out.println("There already is a file named "
                                       + fileName);
                System.out.println("Enter a different file name:");
                fileName = keyboard.readLine( );
                fileName = fileName.trim( );
                fileObject = new File(fileName);
            }
        }
        catch(IOException e)
        {
            System.out.println("Error reading from the keyboard. ");
            System.exit(0);
        }
 
        PrintWriter outputStream = null;
        try
        {
            outputStream = 
                 new PrintWriter(new FileOutputStream(fileName));
        }
        catch(FileNotFoundException e)
        {
            System.out.println("Error opening the file " + fileName);
            System.exit(0);
        }
 
        System.out.println("Writing \""  + line + "\"");
        System.out.println("to the file "  + fileName);
        outputStream.println(line);
 
        outputStream.close( );
        System.out.println("Writing completed.");
    }
}