cloc src

package test;

public class Main {

/**
 * A javadoc comment.
 * @param args
 */
public static void main(String[] args) {
    System.out.println("/* This isn't a comment */");
    /* This is a comment */
    //Comment
    System.out.println("//Not comment");
}
//Comment
}

Note :- This program is not optimized for performance, performance is not an attribute i care about here. I chose not to use Pattern.compile() among many other decisions.

I count the empty lines, comment lines and lines of code separately.

if there is any sentence which has a some tabs or just spaces, they are counted as
empty lines. They match with the regular expression s*
s - any whitespace character (ntb)
 * - this means there can be any number of whitespace characters


comment lines are the ones that match any of the following conditions :-
1) have a // outside of a string
2) have a /* some comment */
3) have a /* but the '*/' is not found on the same line

The regular expression for the above can be found inside the code!

Lines of code are the ones that end in ')' , '}' , '{' or ';' (one problem with this approach is that it does not count lines that have code followed by comment as a line of code)

The summary of these three types of lines are provided by this program.

//Below is the working code

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class CountComment {

    public static void main(String[] args) {
        String line="";
        int count=0;
        try {
            BufferedReader br=new BufferedReader(new FileReader("./src/numbers/comment.txt"));
                while((line=br.readLine())!=null)
                {
                    if(line.startsWith("//"))
                        count++;
                    if(line.startsWith("/*"))
                    {
                        count++;
                        while(!(line=br.readLine()).endsWith("'*'"))
                        {
                        count++;
                        break;
                        }
                    }

                }
                br.close();
        }
        catch (FileNotFoundException e) {
            e.printStackTrace();
        }
             catch (IOException e) {
                e.printStackTrace();
            }

        System.out.println("count="+count);
        }


    }