//FileClassDemo.java
//Demonstrates use of the class File with text files.
//
import java.io.File;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

public class FileClassDemo
{
    public static void main(String[] args)
    {
        String name = null;
        System.out.print("I will show you the first line ");
        System.out.println("in a text file you name.");
        System.out.println("The file must contain one or more lines.");
        System.out.print("Enter file name: ");
        Scanner keyboard = new Scanner(System.in);

        name = keyboard.nextLine();
        File fileObject = new File(name);

        while ( (!fileObject.exists()) || (!fileObject.canRead()) )
        {
            if (!fileObject.exists())
              System.out.println("No such file.");
            else // ! fileObject.canRead()
              System.out.println("That file is not readable.");
            System.out.print("Enter file name again: ");
            name = keyboard.nextLine();
            fileObject = new File(name);
        }
        try
        {
            BufferedReader fileInput = new BufferedReader(new FileReader(name));
            System.out.println("The first line in the file is:");
            String firstLine = fileInput.readLine( );
            System.out.println(firstLine);
            fileInput.close();
        }
        catch(IOException e)
        {
            System.out.println("Problem reading from file.");
        }
    }
}