package filesample;

import java.io.File;
import java.util.Scanner;

/* A short sample program designed to demonstrate how to use a Scanner to 
 * read text input from a text file. The code here assumes that the there
 * is some data to be read from a text file named 'data.txt'. The first line
 * in the file is an integer that tells us how many lines of text follow
 * in the file. The program will read that integer and then drop into a 
 * loop that reads that many lines of text from the file and then echoes
 * each line read to System.out.
 */
public class FileSample {

     public static void main(String[] args) {
        Scanner in = null;
        
        /* To read from a text file we construct a Scanner initialized with a 
         * File object. Unfortunately, the Scanner's constructor may throw
         * an exception if the file does not exist or it can not be opened.
         * 
         * To cope with the exception, we have to wrap the offending code in a
         * try block and set up a catch block to catch the exception and exit
         * the program if opening the file fails.
         */
        try {
            in = new Scanner(new File("data.txt"));
        }
        catch(Exception ex)
        {
            System.out.println("An exception occured while opening the file.");
            System.out.println(ex.getMessage());
            System.exit(1);
        }
        
        /* Once the file is open we can read data from it through the Scanner. 
         * We read the integer at the start of the file and do a nextLine to 
         * move down to the next line in preparation for reading the lines of
         * text.
         */
        int numberOfStrings = in.nextInt();
        in.nextLine();
        // This loops reads and echos the lines of text from the file. 
        for(int n = 0;n < numberOfStrings;n++) {
            String nextString = in.nextLine();
            System.out.println(nextString);
        }
    }
}