java - 具有不同表达式类型的嵌套开关: ArrayIndexOutOfBoundsException -4

Question

我附上我的代码供您引用。当我执行以下乘法功能代码时，我收到以下错误，

线程“main”中的异常 java.lang.ArrayIndexOutOfBoundsException: -4 在 choice2.main(choice2.java:99)

仅供引用 - 该程序对于该程序中的所有其他功能都运行良好。

代码:

import java.util.*;

class choice2 {
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        @SuppressWarnings("resource")
        Scanner S = new Scanner(System.in);

        int ch, subch;
        String Target = null;
        int codePos = 0, a, b, c = 0;

        String[] Arith = {"Add", "Sub"};
        String[] Mult = {"Multiplication", "Division", "Modulas" };

        System.out.println("1.Arithmatic");
        System.out.println("2.Mult/Div/Mod");
        System.out.println("0 to Exit from Menu");
        System.out.println("Enter your Choice");

        ch = S.nextInt();

        switch (ch) {
        case 1:
            System.out.println("1.Addition");
            System.out.println("2.Subtraction");
            System.out.println("9.Goback to Main Menu");
            subch = S.nextInt();

            if (subch == 1)
                Target = "Add";
            else
                Target = "Sub";

            codePos = Arrays.binarySearch(Arith, Target);

            switch (Arith[codePos]) {

            case "Add":
                System.out.println("Enter value for A");
                a = S.nextInt();
                System.out.println("Enter value for B");
                b = S.nextInt();

                c = a + b;

                System.out.println("The result is " + c);

                break;

            case "Sub":
                System.out.println("Enter value for A");
                a = S.nextInt();
                System.out.println("Enter value for B");
                b = S.nextInt();

                c = a - b;

                System.out.println("The result is " + c);

                break;
            }
            break;

        case 2:
            System.out.println("1.Multiplication");
            System.out.println("2.Division");
            System.out.println("3.Modulas");
            System.out.println("9.Goback to Main Menu");

            subch = S.nextInt();

            switch (subch) {

            case 1:
                Target = "Multiplication";
                break;

            case 2:
                Target = "Division";
                break;

            case 3:
                Target = "Modulas";
                break;

            default:
                System.out.println("Invalid Value");
            }

            System.out.println(codePos);
            System.out.println(Target);

//          codePos = Arrays.binarySearch(Mult, Target);
            codePos = Arrays.binarySearch(Mult, 0, Mult.length, Target);
            switch (Mult[codePos]) {

            case "Multiplication":
                System.out.println("Enter value for A");
                a = S.nextInt();
                System.out.println("Enter value for B");
                b = S.nextInt();

                c = a * b;

                System.out.println("The result is " + c);

                break;

            case "Division":
                System.out.println("Enter value for A");
                a = S.nextInt();
                System.out.println("Enter value for B");
                b = S.nextInt();

                c = a / b;

                System.out.println("The result is " + c);

                break;

            case "Modulas":
                System.out.println("Enter value for A");
                a = S.nextInt();
                System.out.println("Enter value for B");
                b = S.nextInt();

                c = a % b;

                System.out.println("The result is " + c);

                break;
            }
        }
        System.out.println("Exit from program");
    }
}

Answer 1

如果找不到该值，

Arrays.binarySearch 将返回负数。另外，要使用二分搜索，必须对数组进行排序，但事实并非如此，这可能会导致您的错误。像这样声明你的数组:

String[] Mult = {"Division", "Modulas", "Multiplication" };