Question

IT Java code

In Lab 8, we are going to re-write Lab 3 and add code to validate user input.

The Body Mass Index (BMI) is a calculation used to categorize whether a person’s weight is at a healthy level for a given height. The formula is as follows:

                bmi = kilograms / (meters²)

                where kilograms = person’s weight in kilograms, meters = person’s height in meters

BMI is then categorized as follows:

Classification	BMI Range
Underweight	Less than 18.5
Normal	18.5 or more, but less than 25.0
Overweight	25.0 or more, but less than 30.0
Obese	30.0 or more

To convert inches to meters:

                meters = inches / 39.37

To convert pounds (lbs) to kilograms:

                kilograms = lbs / 2.2046

Assignment

Ask the user for their weight in pounds and height in inches. Compute their BMI and BMI classification and output the results.

The program must implement and use the following methods:

convertToKilograms – convert pounds to kilograms

convertToMeters – convert inches to meters

calcBMI – take weight in kilograms and height in meters and return the BMI

bmiClassification – take the value for the BMI and return a String with the BMI classification

Use the following code as a starting point for your assignment:

package home;

import java.util.Scanner;

// TODO Student name, date, purpose
public class Main {

    private static Scanner input = new Scanner(System.in);

    private static final String INPUT_ERROR = "Input is not valid, try again";

    public static void main(String[] args) {
        double lbs, inches, meters, kgs, bmi;
        String classification;

System.out.println("Calculate BMI");
lbs = inputWeight();
inches = inputHeight();

       // TODO add code here
    }

   // TODO add your methods here (make them static)
}

Validations

You will include code that will validate all user input. If the user inputs an invalid value, the program will respond with an error message and will ask the user to input the data again (use a do / while loop). Invalid values include:

• Weight or height are less than or equal to zero
• Weight or height contain non-numeric characters

When you get user input, read in the values as Strings. Convert the weight and height String values using the Double.parseDouble() method. Be sure to handle all exceptions. See:

https://docs.oracle.com/javase/10/docs/api/java/lang/Double.html#parseDouble(java.lang.String)

for details.

You will create and use two new methods:

inputWeight() – return a double with the user’s valid weight in pounds

inputHeight() – return a double with the user’s valid height in inches

Example Output

Calculate BMI

Enter weight (lbs): -17

Input is not valid, try again

Enter weight (lbs): 0

Input is not valid, try again

Enter weight (lbs): abcd

Input is not valid, try again

Enter weight (lbs): 200

Enter height (inches): -12

Input is not valid, try again

Enter height (inches): 0

Input is not valid, try again

Enter height (inches): 1abc

Input is not valid, try again

Enter height (inches): 72

Your BMI is 27.124767811523153

Your BMI classification is Overweight

coding:

package HOME;

import java.util.Scanner;

public class Main {

   import java.util.Scanner;
    public class Main {

        private static Scanner input = new Scanner(System.in);
        private static final String INPUT_ERROR = "Input is not valid, try again";

        public static void main(String[] args) {
            double lbs, inches, meters, kgs, bmi;
            String classification;
            System.out.println("Calculate BMI");
            do {
                lbs = inputWeight();
            } while (lbs <= 0.0);
            do {
                inches = inputHeight();
            } while (inches <= 0.0);
            kgs = convertToKilograms(lbs);
            meters = convertToMeters(inches);
            bmi = calcBMI(kgs, meters);
            System.out.println("Your BMI is " + bmi);
            System.out.println(bmiClassification(bmi));
        }
        private static double inputWeight() {
            System.out.print("Enter weight (lbs): ");
            String pounds = input.nextLine();
            try {
                double value = Double.parseDouble(pounds);
                if (value <= 0.0) {
                    value = 0.0;
                    System.out.println(INPUT_ERROR);
                }
                return value;
            } catch (NullPointerException ex) {
                System.out.println(INPUT_ERROR);
                return 0.0;
            } catch (NumberFormatException ex) {
                System.out.println(INPUT_ERROR);
                return 0.0;
            } catch (Exception ex) {
                System.out.println(INPUT_ERROR);
                return 0.0;
            }
        }
        private static double inputHeight() {
            System.out.print("Enter height (inches):");
            String height = input.nextLine();
            try {
                double value = Double.parseDouble(height);
                if (value <= 0.0) {
                    value = 0.0;
                    System.out.println(INPUT_ERROR);
                }
                return value;
            } catch (NullPointerException ex) {
                System.out.println(INPUT_ERROR);
                return 0.0;
            } catch (NumberFormatException ex) {
                System.out.println(INPUT_ERROR);
                return 0.0;
            } catch (Exception ex) {
                System.out.println(INPUT_ERROR);
                return 0.0;
            }
        }
        private static double convertToKilograms(double lbs) {
            return (lbs / 2.2046);
        }
        private static double convertToMeters(double inches) {
            return (inches / 39.37);
        }
        private static double calcBMI(double weight, double height) {
            return (weight / (height * height));
        }
        private static String bmiClassification(double bmi) {
            if (bmi < 18.5) {
                return "Your BMI classification is Underweight";
            } else if (bmi >= 18.5 && bmi < 25) {
                return "Your BMI classification is Normal";
            } else if (bmi >= 25 && bmi < 30) {
                return "Your BMI classification is Overweight";
            } else if (bmi > 30) {
                return "Your BMI classification is Obese";
            } else {
                return "";
            }
        }
    }
}

Answer 1

Please find the answer below, have corrected some exception part

Main.java

import java.util.Scanner;

public class Main {
  private static Scanner input = new Scanner(System.in);
  private static final String INPUT_ERROR = "Input is not valid, try again";

  public static void main(String[] args) {
    double lbs, inches, meters, kgs, bmi;
    String classification;
    System.out.println("Calculate BMI");
    do {
      lbs = inputWeight();
    } while (lbs <= 0.0);
    do {
      inches = inputHeight();
    } while (inches <= 0.0);
    kgs = convertToKilograms(lbs);
    meters = convertToMeters(inches);
    bmi = calcBMI(kgs, meters);
    System.out.println("Your BMI is " + bmi);
    System.out.println(bmiClassification(bmi));
  }

  private static double inputWeight() {
    System.out.print("Enter weight (lbs): ");
    String pounds = input.nextLine();
    try {
      double value = Double.parseDouble(pounds);
      if (value <= 0.0) {
        value = 0.0;
        System.out.println(INPUT_ERROR);
      }
      return value;
    } catch (Exception ex) {
      System.out.println(INPUT_ERROR);
      return 0.0;
    }
  }

  private static double inputHeight() {
    System.out.print("Enter height (inches):");
    String height = input.nextLine();
    try {
      double value = Double.parseDouble(height);
      if (value <= 0.0) {
        value = 0.0;
        System.out.println(INPUT_ERROR);
      }
      return value;
    } catch (Exception ex) {
      System.out.println(INPUT_ERROR);
      return 0.0;
    }
  }

  private static double convertToKilograms(double lbs) {
    return (lbs / 2.2046);
  }

  private static double convertToMeters(double inches) {
    return (inches / 39.37);
  }

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

  private static String bmiClassification(double bmi) {
    if (bmi < 18.5) {
      return "Your BMI classification is Underweight";
    } else if (bmi >= 18.5 && bmi < 25) {
      return "Your BMI classification is Normal";
    } else if (bmi >= 25 && bmi < 30) {
      return "Your BMI classification is Overweight";
    } else if (bmi > 30) {
      return "Your BMI classification is Obese";
    } else {
      return "";
    }
  }
}

Output:

Please let us know in the comments if you face any problems.