Chapter 21 Exercise 13, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

21.13 (Baby name popularity ranking)
Revise Programming Exercise 21.11 to prompt the user to enter year,
gender, and name and display the ranking for the name. Prompt the
user to enter another inquiry or exit the program.

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Exercise_13 {


    public static void main(String[] args) {

        HashMap<String, Integer>[][] babyNamesMapArray = new HashMap[2][10];

        for (int j = 0; j < babyNamesMapArray.length; j++)
            for (int i = 0; i < babyNamesMapArray[j].length; i++)
                babyNamesMapArray[j][i] = new HashMap<>();
        File[] files = new File("/Users/Kernel/GitHub/intro-to-java-10th-edition/src/text-files")
                .listFiles((dir, name) -> name.matches("babynamesranking.*"));

        Arrays.sort(files);

        for (int i = 0; i < files.length; i++) {
            try(Scanner in = new Scanner(files[i])) {

                int gender = 0;
                String rank = "";
                while (in.hasNext()) {
                    if (gender == 0)
                        rank = in.next() + "";
                    String name = in.next();
                    String popularity = in.next(); // trash for now
                    babyNamesMapArray[gender][i].put(name, Integer.parseInt(rank));

                    if (gender == 1)
                        gender = 0;
                    else
                        gender++;
                }

            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        String again;
        Scanner scanner = new Scanner(System.in);
        do {
            System.out.print("Enter a year (2001-2010): ");
            String yearString = scanner.next();
            int year = Integer.parseInt(yearString) - 2001;

            System.out.print("Enter a gender (male/female): ");
            String genderString = scanner.next();
            int gender = (genderString.equalsIgnoreCase("male")) ? 0 : 1;

            System.out.print("Enter a name: ");
            String name = scanner.next();

            HashMap<String, Integer> hashMap = babyNamesMapArray[gender][year];

            String formattedName = makeFirstCapital(name);
            if (hashMap.containsKey(formattedName)) {
                System.out.println(genderString + " " + name + " is rank #" + hashMap.get(formattedName) + " in year " + yearString);
            } else {
                System.out.println("No match was found.");
            }


            System.out.print("Enter another enquiry? ");
            again = scanner.next();
        } while (!again.equalsIgnoreCase("no"));

    }

    public static String makeFirstCapital(String word) {

        return Character.toUpperCase(word.charAt(0)) + word.substring(1).toLowerCase();
    }

}