面试题08：Calculate BMI

Write function bmi that calculates body mass index (bmi = weight / height ^ 2).
if bmi <= 18.5 return “Underweight”
if bmi <= 25.0 return “Normal”
if bmi <= 30.0 return “Overweight”
if bmi > 30 return “Obese”
这道题目不难，主要的看点在于if else 的写法。

public static String bmi(double weight, double height) {
        double args = weight / (height * height) ;
        if (args <= 18.5) return "Underweight" ;
        if (args <= 25.5 && args > 18.5) return "Normal";
        if (args <= 30 && args > 25.5) return "Overweight";
        if (args > 30) return "Obese"
        return null;
      }
    @Test
    public void testBMI() {
        assertEquals("Normal", Calculate.bmi(80, 1.80));
    }

这种写法是不算太好的，下面这种比较合适。

public static String bmi(double weight, double height) {
        double args = weight / (height * height) ;
        if (args > 30) return "Obese";
        else if (args > 25.5) return "Overweight";
        else if (args > 18.5) return "Normal";
        else return "Underweight" ;
      }
    @Test
    public void testBMI() {
        assertEquals("Normal", Calculate.bmi(80, 1.80));
    }

这种写法比较合理，else if 满足的条件是：不仅满足当前条件，还满足前一个条件的反条件。