7Boom

package Tester;

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

public class Boom7Tester {
    public static void main(String[] args){
        String fileName = "SevenBoom.boom";
        int num = 39;
        try {
            writeFile(fileName, num);
            System.out.println(numOfBooms(fileName));
        }catch(FileNotFoundException fnfe) {
            System.out.println(fnfe);
        }
    }

    public static void writeFile(String fName, int n) throws FileNotFoundException {
        File file = new File(fName);
        PrintWriter pw = new PrintWriter(file);
        for(int i = 1; i <= n; i++) {
            if (i % 7 == 0 || contains7Digit(i)) {
                pw.println("boom");
            } else {
                pw.println(i);
            }
        }
        pw.close();
    }

    public static boolean contains7Digit(int number) {
        while(number/10 > 0) {
            if(number % 10 == 7) {
                return true;
            }
            number /= 10;
        }
        return false;
    }

    public static int numOfBooms(String fileName) throws FileNotFoundException{
        File f = new File(fileName);
        Scanner sc = new Scanner(f);
        int booms = 0;
        while(sc.hasNext()) {
            if(sc.nextLine().equals("boom")) {

                booms += 1;
            }
        }
        return booms;
    }
}