java - 寻找退出系统或停止代码的方法

Question

下面的当前代码会在输入越界输入时导致错误发生，然后将错误打印到屏幕上，这就是我想要的。但问题是，代码出错后，它仍然打印答案，而不是停止。我尝试在消息下方的 if 代码中放入系统退出语句，但随后 IDE 提醒我，由于某种原因，else 需要一个“if”。有没有办法在代码打印到屏幕后停止所有功能

    public Driver(double[] test) throws IllegalArgumentException
    {
        scoreArray = new double[test.length];
        for (int i = 0; i < test.length; i++)
        {
            if (test[i] < 0 || test[i] > 100)
                System.err.println("Test scores must have a value less than 100 and greater than 0.");
               // throw new IllegalArgumentException("Test scores must have a value less than 100 and greater than 0.");
            else
                scoreArray[i] = test[i];
        }
    }

完整代码我使用的IDE是netbeans

package driver;
import java.util.Scanner;
import java.text.DecimalFormat; 


public class Driver
{
    private double[] scoreArray;

    public Driver(double[] test) throws IllegalArgumentException
    {
        scoreArray = new double[test.length];
        for (int i = 0; i < test.length; i++)
        {
            if (test[i] < 0 || test[i] > 100)
                System.err.println("Test scores must have a value less than 100 and greater than 0.");
               // throw new IllegalArgumentException("Test scores must have a value less than 100 and greater than 0.");
            else
                scoreArray[i] = test[i];
        }
    }

    public double getAverage()
    {
        double total = 0.0;
        for (int i = 0; i < scoreArray.length; i++)
            total += scoreArray[i];

        return (total / scoreArray.length);
    }

    public static void main(String[] args)
    {  
        int score = 0;
       // int scores = 0;

        Scanner userInput = new Scanner(System.in);

        System.out.print("Enter number of test scores:");
        score = userInput.nextInt();

        double[] scoreArray = new double[score];

        for (int i = 0; i <= score - 1; i++)
        {    
            System.out.print("Enter test score " + (i + 1)+ ":");
            //scoreArray[scores] = userInput.nextDouble();  
            scoreArray[i] = userInput.nextDouble();
        }
        DecimalFormat ft = new DecimalFormat("####");
        ft = new DecimalFormat("0.0"); 
        Driver testScore  = new Driver(scoreArray);
        //System.out.println(driver.getAverage);
        System.out.println(ft.format(testScore.getAverage()));
    }
}

Answer 1

如果您想在 if 中放置两条语句，则需要将它们放在大括号 {} 内。常识是始终在 if 语句中使用大括号。这就是为什么当您尝试在 if 和 else 之间添加另一个语句时编译器告诉您这是一个错误。

像这样:

if (test[i] < 0 || test[i] > 100) {
    System.err.println("Test scores must have a value less than 100 and greater than 0.");
    throw new IllegalArgumentException("Test scores must have a value less than 100 and greater than 0.");
} else { 
    scoreArray[i] = test[i];
}