bmi = weight / (height * height);

System.out.printf("bmi: %.2f****\n****", bmi);
if (bmi < 18.5) {
    System.out.println("过轻");
} else if (bmi <= 25) {
    System.out.println("正常");
} else if (bmi <= 28) {
    System.out.println("过重");
} else if (bmi <= 32) {
    System.out.println("肥胖");
} else {
    System.out.println("非常肥胖");
}