主方法中的ArrayIndexOutOfBounds异常 [英] ArrayIndexOutOfBounds exception in main method

问题描述

我遇到数组绑定错误，但我认为数组从0开始，那么这段代码有什么问题呢?

I am getting array bound error but to my mind, array starts from 0, so what is wrong with this code?

public class Quadratic {

    public static void main(String[] args) {
        double b = Double.parseDouble(args[0]);
        double c = Double.parseDouble(args[1]);

        double discriminant = b*b - 4.0*c;
        double sqroot = Math.sqrt(discriminant);

        double root1 = (-b + sqroot)/ 2.0;
        double root2 = (-b - sqroot)/ 2.0;

        System.out.println(root1);
        System.out.println(root2);
    }
}

推荐答案

保护自己:保持防御.

    public class Quadratic {

    public static void main(String[] args) {

        if (args.length> 1) {
            double b = ((args.length > 0) ? Double.parseDouble(args[0]) : 0.0);
            double c = ((args.length > 1) ? Double.parseDouble(args[1]) : 0.0);

            double discriminant = b*b - 4.0*c;
            double sqroot = Math.sqrt(discriminant);

            double root1 = (-b + sqroot)/ 2.0;
            double root2 = (-b - sqroot)/ 2.0;

            System.out.println(root1);
            System.out.println(root2);
        } else {
            System.out.println("two arguments are required: b and c, please");
        }
    }
}

如果判别结果是否定的，会发生什么?如果为零怎么办?

What happens if the discriminant is negative? What if it's zero?

为什么要限制a = 1的情况?

Why are you restricting yourself to the case where a = 1?

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