import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;

/**
 * Reads numbers from a file named data.dat and writes them to a file
 * named result.dat in reverse order.  The input file should contain
 * exactly one real number per line.
 */
public class ReverseFileWithScanner {

    public static void main(String[] args) {

        Scanner data;     // Character input stream for reading data.
        PrintWriter result;  // Character output stream for writing data.

        ArrayList<Double> numbers;  // An ArrayList for holding the data.

        numbers = new ArrayList<Double>();

        try {  // Create the input stream.
            data = new Scanner(new File("data.dat"));
        }
        catch (FileNotFoundException e) {
            System.out.println("Can't find file data.dat!");
            return;  // End the program by returning from main().
        }

        try {  // Create the output stream.
            result = new PrintWriter("result.dat");
        }
        catch (FileNotFoundException e) {
            System.out.println("Can't open file result.dat!");
            System.out.println("Error: " + e);
            data.close();  // Close the input file.
            return;        // End the program.
        }

        while ( data.hasNextDouble() ) {  // Read until end-of-file.
            double inputNumber = data.nextDouble();
            numbers.add( inputNumber );
        }

        // Output the numbers in reverse order.

        for (int i = numbers.size()-1; i >= 0; i--)
            result.println(numbers.get(i));

        System.out.println("Done!");

        data.close();
        result.close();

    }  // end of main()

} // end class ReverseFileWithScanner