简单的加减乘除（递归）

package method;

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        //简易的计算器
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入第一个值：");
        double x = scanner.nextDouble();
        System.out.println("请输入第二个值：");
        double y = scanner.nextDouble();
        System.out.println("请输入符号：");
        String operator = scanner.next();
        switch (operator){
            case "+":
                add(x, y);
                System.out.println(x+y);
                break;
            case "-":
                sub(x, y);
                System.out.println(x-y);
                break;
            case "*":
                mul(x, y);
                System.out.println(x*y);
                break;
            case "/":
                div(x, y);
                System.out.println(x/y);
                break;
        }
    
    }
public static double add(double x,double y){
        return x+y;
    }
    public static double sub(double x,double y){
        return x-y;
    }
    public static double mul(double x,double y){
        return x*y;
    }
    public static double div(double x,double y){
        return x/y;
    }
}