Question

Need help with this java practice question. Need to complete main method.

Adding line numbers to the file.

1. Begin with the supplied file Template.java.

public class Template {
  static final String INPUT_FILE = "test.txt";
static final String OUTPUT_FILE = "output.txt";
    public static void main(String[] args) {
    }//main
  }
2. Complete the main method so that it will read in the supplied file test.txt and write out a modified version of this file as output.txt. (These two names are predefined for you as global constants.) The output file should be the same as the input file, except that every line should have a line number added to the front, in the format shown below. The supplied file test.txt contains:
This is the top line

The previous one is blank.
Short one.
This is the last one.
Your program should create an output file output.txt which contains:
1: This is the top line
2:
3: The previous one is blank.
4: Short one.
5: This is the last one.

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. If not, PLEASE let me know before you rate, I’ll help you fix whatever issues. Thanks

// Template.java

import java.io.File;

import java.io.FileNotFoundException;

import java.io.PrintWriter;

import java.util.Scanner;

public class Template {

      static final String INPUT_FILE = "test.txt";

      static final String OUTPUT_FILE = "output.txt";

      public static void main(String[] args) throws FileNotFoundException {

            // opening input file to read. make sure test.txt file exist in the

            // current working directory / root directory of your project. otherwise

            // the system will throw exception.

            Scanner scanner = new Scanner(new File(INPUT_FILE));

            // opening output.txt file to write

            PrintWriter writer = new PrintWriter(new File(OUTPUT_FILE));

            // variable to store current line number

            int lineNumber = 1;

            // looping as long as there is more data to read in the file

            while (scanner.hasNext()) {

                  // reading next line

                  String line = scanner.nextLine();

                  // writing line number followed by a colon and space and then the

                  // read line.

                  writer.println(lineNumber + ": " + line);

                  //updating line number

                  lineNumber++;

            }

            //closing files, saving changes

            scanner.close();

            writer.close();

      }// main

}