JAVA实现在控制台的计算器

使用switc--case实现，定义两个变量接收键盘输入的值，定义运算的几个方法，在选择运算的方式，赋值、调用方法运算输出结果。

代码如下：

public class JiSuanQi {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
            double a1=0;
            double a2=0;
            System.out.println("输入运算方法的编号");
            System.out.println("1、加法");
            System.out.println("2、减法");
            System.out.println("3、乘法");
            System.out.println("4、除法");
            int i = scanner.nextInt();
            switch (i){
                case 1:
                    System.out.print("输入执行加法的两个数值：");
                     a1 = scanner.nextDouble();
                     a2 = scanner.nextDouble();
                    System.out.println("结果是："+jia(a1,a2));break;
                case 2:
                    System.out.print("输入执行减法的两个数值：");
                     a1 = scanner.nextDouble();
                    a2 = scanner.nextDouble();
                    System.out.println("结果是："+jian(a1,a2));break;
                case 3:
                    System.out.print("输入执行乘法的两个数值：");
                     a1 = scanner.nextDouble();
                     a2 = scanner.nextDouble();
                    System.out.println("结果是："+chen(a1,a2));break;
                case 4:
                    System.out.print("输入执行除法的两个数值：");
                     a1 = scanner.nextDouble();
                     a2 = scanner.nextDouble();
                    System.out.println("结果是："+chu(a1,a2));break;
                default:
                    System.out.println("格式错误！");
            }
            scanner.close();
    }
    public static double jia(double i,double j){
       return i+j;
    }
    public static double jian(double i,double j){
        return i-j;
    }
    public static double chen(double i,double j){
        return i*j;
    }
    public static double chu(double i,double j){
        return i/j;
    }
}