Question

Using Java programming to answer this question.

Write a method countLines(String inFilename) of a class FileUtility which reads a binary byte file with name inFilename using FileInputStream. The method returns the no. of lines containing comments starting with "//" with optional spaces (but not other characters) before it. Each line is terminated by '\n'. You may write other methods if necessary. Handle possible exception by outputting a suitable message if an exception occurs.

Answer 1

CODE:

import java.io.File;
import java.io.FileInputStream;

public class FileContents {
   public static int countLines(String inFilename) {
       int noOfLinesCount = 0;
       File file = new File(inFilename);
       try (FileInputStream fileInputStream = new FileInputStream(file)) {
           int line;
           // Reading character by character form fileInputStream Object
           while ((line = fileInputStream.read()) != -1) {
               // If one character is '/'
               if ((char) line == '/') {
                   // Then we are seaching for next character that it has to be '/' for success
                   // comment
                   if ((char) (line = fileInputStream.read()) == '/') {
                       // Increment the lines count
                       noOfLinesCount++;
                   }
               }
           }
       } catch (Exception e) {
           System.err.println("File not found");
           e.printStackTrace();
       }
       return noOfLinesCount;
   }

   public static void main(String[] args) {
       System.out.println("Total number of Commented lines are :: " + countLines("contents.txt"));
   }
}

contents.txt:

//London
China //Beijing
India - Delhi
//SaudiArabia
US //Wahsington

CODE SCREENSHOT WITH OUTPUT FOR ABOVE FILE CONTENTS:

Hope this will help you. Let me know if have any queries??..