Conditional Execution - Building Java Programs: A Back to Basics Approach - page 276

Table 4.7 Weight Status by BMI

BMI Weight status

below 18.5 underweight

18.5-24.9 normal

25.0-29.9 overweight

30.0 and above obese

In the sample execution we also see a report of the person's weight status. The CDC
website includes the information shown in Table 4.7. There are four entries in this table,
so we need four different println statements for the four possibilities. We will want to
use if or if/else statements to control the four println statements. In this case, we
know that we want to print exactly one of the four possibilities. Therefore, it makes
most sense to use a nested if/else construct that ends with an else .
But what tests do we use for the nested if/else ? If you look closely at Table 4.7,
you will see that there are some gaps. For example, what if your BMI is 24.95? That
number isn't between 18.5 and 24.9 and it isn't between 25.0 and 29.9. It seems clear
that the CDC intended its table to be interpreted slightly differently. The range is
probably supposed to be 18.5-24.999999 (repeating), but that would look rather odd
in a table. In fact, if you understand nested if/else statements, this is a case in
which a nested if/else construct expresses the possibilities more clearly than a
table like the CDC's. The nested if/else construct looks like this:

if (bmi1 < 18.5) {
System.out.println("underweight");
} else if (bmi1 < 25) {
System.out.println("normal");
} else if (bmi1 < 30) {
System.out.println("overweight");
} else { // bmi1 >= 30
System.out.println("obese");

}

So, putting all this together, we get a complete version of the first program:

1 import java.util.*;
2
3 public class BMI1 {
4 public static void main(String[] args) {

5 Scanner console = new Scanner(System.in);

6
7

System.out.println("Enter next person's information:");

8 System.out.print("height (in inches)? ");