读取用户输入时发生 Java ArrayIndexOutOfBoundsException

Question

这个问题已经有答案了:

How can I avoid ArrayIndexOutOfBoundsException or IndexOutOfBoundsException? [duplicate] (2 个回答)

已关闭 7 年前。

每当我尝试使用高于 eq[0] 的任何值时，我最终得到 ArrayIndexOutOfBoundsException .

我的代码:

import java.util.Scanner;

public class Calc{
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        String[] eq=in.next().split(" ");

        double a=Double.parseDouble(eq[0]);
        double b=Double.parseDouble(eq[-1]);

        if(eq[1]=="+"){
            System.out.println(">>"+String.valueOf(a+b));
        }else if(eq[1]=="-"){
            System.out.println(">>"+String.valueOf(a-b));
        }else if(eq[1]=="/"){
            System.out.println(">>"+String.valueOf(a/b));
        }else if(eq[1]=="*"){
            System.out.println(">>"+String.valueOf(a*b));
        }
    }
}

Answer 1

eq[-1] -1 index is problem

eq[1]=="+" // logical error use equals() method to compare String.

           Scanner in=new Scanner(System.in);
            String[] eq=in.nextLine().split(" "); // use nextLine() instead of next().
        
            double a=Double.parseDouble(eq[0]);// 1st operand
            double b=Double.parseDouble(eq[2]);// 3rd operand

            if(eq[1].equals("+")){ //operator // compare string with equals method not with (==).
                System.out.println(">>"+String.valueOf(a+b));
            }else if(eq[1].equals("-")){
                System.out.println(">>"+String.valueOf(a-b));
            }else if(eq[1].equals("/")){
                System.out.println(">>"+String.valueOf(a/b));
            }else if(eq[1].equals("*")){
                System.out.println(">>"+String.valueOf(a*b));
            }