How to count Java comments of a program that is stored in a text file?

You can read the contents of a file using the Scanner class and You can find the comments in a particular line using contains() method.

Example

import java.io.*;
import java.util.Scanner;
public class FindingComments {
   public static void main(String[] args) throws IOException {
      Scanner sc = new Scanner(new File("HelloWorld"));
      String input;
      int single = 0;
      int multiLine = 0;
      while (sc.hasNextLine()) {
         input = sc.nextLine();
         if (input.contains("/*")) {
            multiLine ++;
         }
         if(input.contains("//")) {
            single ++;
         }
      }
      System.out.println("no.of single line comments ::"+single);
      System.out.println("no.of single line comments ::"+multiLine);
   }
}

Contents of the file HelloWorld −

Public class SampleProgram{
   /* This is my first java program.
      * This will print ‘Hello World’ as the output
   */
   Public static void main(String args[]){
      //Prints Hello World
      System.out.println("Hello World");
   }
}

Output

no.of single line comments ::1
no.of single line comments ::1