Bmi Calculator

Bmi.java

import java.text.DecimalFormat;
import java.util.Scanner;

public class Bmi {

    private static Scanner scanner;

    public static void main(String[] args) {
        scanner = new Scanner(System.in);
        System.out.print("Enter National [TH, JP]: ");
        String national = scanner.next();

        System.out.print("Enter weight[kg]: ");
        double weight = scanner.nextDouble();

        System.out.print("Enter height[cm]: ");
        double height = scanner.nextDouble();

        double bmi = bmiCal(height, weight);

        System.out.print(checkNation(national, bmi));
    }

    private static String checkNation(String national, double bmi) {
        DecimalFormat dc = new DecimalFormat("0.00");
        if (national.equalsIgnoreCase("TH")) {
            return national = "You are Thai: " + dc.format(bmi) + " is " + rateThai(bmi);
        } else if (national.equalsIgnoreCase("JP")) {
            return national = "You are Japan:" + dc.format(bmi) + " is " + rateJapan(bmi);
        } else {
            return national = "Not found nation";
        }
    }

    private static double bmiCal(double height, double weight) {
        return weight / ((height / 100) * (height / 100));
    }

    private static String rateThai(double bmi) {
        if (bmi > 30.0) {
            return "Obese";
        } else if (bmi >= 23.0 && bmi <= 29.9) {
            return "Overweight";
        } else if (bmi >= 18.5 && bmi <= 22.9) {
            return "Normal";
        } else {
            return "lowerweight";
        }
    }

    private static String rateJapan(double bmi) {
        if (bmi > 25.0) {
            return "Obese";
        } else if (bmi >= 23.0 && bmi <= 24.9) {
            return "Overweight";
        } else if (bmi >= 18.5 && bmi <= 22.9) {
            return "Normal";
        } else {
            return "lowerweight";
        }
    }

}