Java寫一個簡單的計算器，能計算加減乘除,接收用戶輸入並能夠循環接收數據

package com.lyn.Methon;

import java.util.Scanner;

public class CalDemo {
    //寫一個計算器，要求能計算加減乘除，並能夠循環接收數據，且接收用戶輸入
    //寫4個方法，加減乘除
    //利用循環+switch進行用戶交互
    //傳遞需要操作的兩個數，並輸出結果
    public static void main(String[] args) {
        while(true){
            System.out.println("請輸入計算類型(+,-,*,/) ,或使用quit退出 ");
            Scanner scanner = new Scanner(System.in);
            String cal = scanner.nextLine();
            if (cal.equals("quit")){
                System.out.println("已退出計算器");
                break;
            }else {
                System.out.println("輸入要進行計算的兩個數,回車分割：");
                switch (cal) {
                    case "+":
                        Scanner num1 = new Scanner(System.in);
                        double addNum1 = num1.nextDouble();
                        Scanner num2 = new Scanner(System.in);
                        double addNum2 = num2.nextDouble();
                        double add = add(addNum1,addNum2);
                        System.out.println(addNum1 + "+" + addNum2 + "=" + add);
                        break;
                    case "-":
                        Scanner num3 = new Scanner(System.in);
                        double minusNum1 = num3.nextDouble();
                        Scanner num4 = new Scanner(System.in);
                        double minusNum2 = num4.nextDouble();
                        double minus = minus(minusNum1,minusNum2);
                        System.out.println(minusNum1+"-"+minusNum2+"="+minus);
                        break;
                    case "*":
                        Scanner num5 = new Scanner(System.in);
                        double multiplyNum1 = num5.nextDouble();
                        Scanner num6 = new Scanner(System.in);
                        double multiplyNum2 = num6.nextDouble();
                        double multiply = multiply(multiplyNum1,multiplyNum2);
                        System.out.println(multiplyNum1+"*"+multiplyNum2+"="+multiply);
                        break;
                    case "/":
                        Scanner num7 = new Scanner(System.in);
                        double divideNum1 = num7.nextDouble();
                        Scanner num8 = new Scanner(System.in);
                        double divideNum2 = num8.nextDouble();
                        double divide = divide(divideNum1,divideNum2);
                        System.out.println(divideNum1+"/"+divideNum2+"="+divide);
                        break;
                }
            }
        }
            
    }
    public static double add(double x, double y){
        return x+y;
    }
    public static double minus(double x, double y){
        return  x-y;
    }
    public static double multiply(double x, double y){
        return x*y;
    }
    public static double divide(double x,double y){
        return  x/y;
    }
        
    
}