java - 这是使用 IllegalArgumentException 的正确方法吗？

Question

我正在尝试完成 Java 作业。这就是它的要求:

Write a class named TestScores. The class constructor should accept an array of the test scores as its argument. The class should have a method that returns the average of the test scores. If an test score in the array is negative or greater than 100, the class should throw an IllegalArgumentException. Demonstrate. I need a file named TestScores and TestScoresDemo.

这就是我目前所拥有的。我知道其中有些错误，我需要帮助修复它:

class TestScores {
    public static void checkscore(int s) {
        if (s<0) throw new IllegalArgumentException("Error: score is negative.");
        else if (s>100) throw new IllegalArgumentException("Error Score is higher then 100");
        else if (s>89)throw new IllegalArgumentException("Your grade is an A");
        else if (s>79 && s<90)throw new IllegalArgumentException("Your grade is an B");
        else if (s>69 && s<80)throw new IllegalArgumentException("Your grade is an C");
        else if (s>59 && s<70)throw new IllegalArgumentException("Your grade is an D");
        else if (s<60)throw new IllegalArgumentException("Your grade is an F");

        {
            int sum = 0; //all elements together
            for (int i = 0; i < a.length; i++)
                sum += a[i];
        }
        return sum / a.length;
    }
}

class TestScoresDemo {
    public static void main(String[] args) {
        int score = 0;
        Scanner scanner = new Scanner(System.in);
        System.out.print(" Enter a Grade number: ");
        String input = scanner.nextLine();
        score = Integer.parseInt(input);
        TestScores.checkscore(score);
        System.out.print("Test score average is" + sum);
    }
}

我知道赋值需要一个 try 语句，因为在我的书中我看到了 IllegalArgumentException。谁能帮我？我使用 Eclipse 作为 IDE。

Answer 1

您的 TestScores 类应该有两个成员:一个接受分数数组的构造函数和一个返回分数平均值的方法。如果测试分数超出范围，分配不完全清楚其中哪些应该抛出 IllegalArgumentException，但我会将其作为构造函数(因为这是有参数的)。

public class TestScores {
    public TestScores(int[] scores) throws IllegalArgumentException {
        // test the scores for validity and throw an exception if appropriate
        // otherwise stash the scores in a field for later use
    }

    public float getAverageScore() {
        // compute the average score and return it
    }
}

您的 TestScoresDemo 类(class)走在正确的轨道上。它首先需要将一组分数收集到一个数组中。然后它应该构造一个 TestScores 对象。这是需要放在 try/catch block 中的内容，因为它可以抛出异常。然后您只需调用 getAverageScore() 并对结果做一些处理。