Explanation

In this problem, you will create a program that reads name, height (in meters), weight (in kilograms), and age from standard input, calculates the BMI (Body Mass Index), classifies the result as Underweight, Normal, or Overweight, and displays a formatted health check card to standard output.

nextDouble() method

nextDouble() is a method that reads decimal numbers (double type). It's used for input that requires decimals, such as height and weight.

Implementation Example

import java.util.Scanner;

Public class Solution {
  Public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
// Read each data
String name = sc.nextLine();
Double height = sc.nextDouble();
Double weight = sc.nextDouble();
Int age = sc.nextInt();

// Calculate BMI
Double bmi = weight / (height * height);

// Determine status
String status;
If (bmi < 18.5) {
  Status = "Underweight";
} else if (bmi < 25.0) {
  Status = "Normal";
} else {
  Status = "Overweight";
}

// Display health check card
System.out.println("===== Health Check Card =====");
System.out.println("Name: " + name);
System.out.println("Height: " + height + "m");
System.out.println("Weight: " + weight + "kg");
System.out.println("Age: " + age + " years old");
System.out.printf("BMI: %.1f%n", bmi);
System.out.println("Status: " + status);
System.out.println("=============================");

  }
}

Key Points

• nextDouble(): Method to read decimal numbers
• double type calculation: Calculations with decimals result in decimals
• printf(): Output with controlled decimal places (%.1f for one decimal place)
• Multiple conditions: Step-by-step judgment using if-else if

Meaning of BMI Calculation

BMI is an index showing the balance between weight and height. Through this calculation, you learn how to create practical programs.