java - 有什么办法可以让这段代码更短吗？

Question

这是一个简单的代码，但是，我想知道是否可以以某种方式使其更短，我什至不知道要寻找什么，所以我不想找人为我重写，我只想有人告诉我应该使用什么方法，如何调用用户在 if 外部编写的变量，或者这些对我有帮助的事情。我是编码新手，很抱歉如果我提出了一个愚蠢的问题。

    System.out.println("Write name: ");
    name = s.nextLine();
    System.out.println("Write last name: ");
    lastName = s.nextLine();
    System.out.println("Write id: ");
    id = s.nextInt();
    System.out.println("Write your average GPA: ");
    average = s.nextDouble();

    System.out.println("Your name is:" +name+ "\nYour last name is: " 
   +lastName+ "\nYour GPA is: " +average+ "\nYearly tuition is: " 
   +tuitionCost);

    if(average >= 9.0){
        System.out.println("Your discount is: 20% off.");
        d = 100-20;
        total = (d * tuitionCost)/100;
        System.out.println("Your yearly tuition is: " +total);
    }
    else if(average <= 8.99 && average >= 8.5){
        System.out.println("Your discount is: 10% off.");
        d = 100-10;
        total = (d * tuitionCost)/100;
        System.out.println("Your yearly tuition is: " +total);
    }
    else if(average <= 8.49 && average >= 8.0){
        System.out.println("Your discount is: 5% off.");
        d = 100-5;
        total = (d * tuitionCost)/100;
        System.out.println("Your yearly tuition is: " +total);
    }
    else{
        System.out.println("You have no discount. Your yearly tuition is: " 
   +tuitionCost);
    }

Answer 1

您可以将折扣变成一类:

class Discount {
    private final List<Tier> tiers = List.of(
        new Tier(0.0, 0), new Tier(8.0, 5), new Tier(8.5, 10), new Tier(9.0, 20));

    private class Tier {
        private final double gpa;
        private final int discount;
    }

    private int discount(double gpa) {
        return tiers.stream().filter(t -> t.gpa <= gpa)
            .mapToDouble(t -> t.discount).max().getAsDouble();
    }

    public double tuition(double gpa, double base) {
        return (1.0 - discount(gpa)/100.0) * base;
    }

    public String discountMessage(double gpa) {
        if (discount(gpa) == 0)
            return "You have no discount";
        else
            return "Your discount is " + discount(gpa) + "%";
    }
}

我遗漏了一些细节，但你明白了。

这可能有点过分了——这取决于等级变化的频率。但它确实满足了 DRY 原则(不要重复自己)。这使您的代码更具弹性:您不太可能在一处更改代码而忘记在其他地方更改它。

您提到要缩短代码。我赞同这样的原则:先求清晰，再求简洁。