Example of using Scanner for I/O from stdin, and files as well as manipulating strings, see video at https://youtu.be/urNqQcqiUTE

FileStringsEx.java

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class FileStringsEx {
    public static boolean hasComment(String s) {
        return s.indexOf("(*") != -1 && s.indexOf("*)") != -1;
    }

    public static void main(String[] args) throws FileNotFoundException {
        Scanner stdin = new Scanner(System.in);
        System.out.println("Enter filename: ");
//        String filename = stdin.nextLine();
        String filename = "data/sunspots.txt";

        Scanner in = new Scanner(new File(filename));
        for (int i = 0; i < 10; i++) {
            if (!in.hasNextLine()) {
                break;
            }
            // else
            String line = in.nextLine();
            if (hasComment(line)) {
                // do something to remove the comment
                int endCommentIndex = line.indexOf("*)");
                line = line.substring(endCommentIndex + 2);
            }
            while (line.charAt(0) == ' ') {
                // remove space
            }

            System.out.println('"' + line + '"');
        }

    }
}

while (line.charAt(0) == ' ') {
                // remove space
}

can be replaced with

line.trim()