Question

Lab Assignment 4B

Modify your program in Lab Assignment 4A to throw an exception if the file does not exist. An error message should result.   Use the same file name in your program as 4A, however, use the new input file in 4B assignment dropbox.

Lab 4A: Write a program that reads a file (provided as attachment to this assignment) and writes the file to a different file with line numbers inserted at the beginning of each line. Test with the input file attached.

For example if file input is:

This is a test

File output should be

1. This is a test

This file contains
lines of text to
determine if you can
properly read and
write from a file
using exceptions.

Answer 1

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

public class WriteLineNumbers {
   public static void main(String[] args){
       try {
           String line;
           int i = 1;
           BufferedWriter bw = null;
           FileWriter fw = null;
           Scanner sc = new Scanner(System.in);
           System.out.println("Enter filename: ");
           String fname=sc.next();
           sc = new Scanner(new File(fname));
           fw = new FileWriter("output.txt");
           bw = new BufferedWriter(fw);
           while (sc.hasNext()) {
               line = sc.nextLine();
               bw.write(i + " " + line + "!\n");
               i++;
           }
           bw.close();
           sc.close();
       }catch(Exception e) {e.printStackTrace();}
       System.out.println("Written Successfully....!!!");
   }
}

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