Java---运算器

一：

代码：

Scanner sc = new Scanner(System.in);
     System.out.println("请输入第1个数：");
     double numOne = sc.nextDouble();
     System.out.println("请输入第2个数：");
     double numTwo = sc.nextDouble();
     System.out.println("请输入：+. -. *. /");
     String action = sc.next();
     if(action.equals("+"))
     {
            System.out.println("结果为："+(numOne + numTwo));
     }
     else if(action.equals("-"))
     {
            System.out.println("结果为："+(numOne - numTwo));
     }
     else if(action.equals("*"))
     {
            System.out.println("结果为："+(numOne * numTwo));
     }
     else if(action.equals("/"))
     {
            System.out.println("结果为："+(numOne / numTwo));
     }
     else
     {
            System.out.println("运算有误！！");
     }

运行结果：

二：

代码：

package Object;

import java.util.Scanner;

public class Calculator {
    double num1;
    double num2;

    public double add(double num1,double num2){
        //double add = num1 + num2;
        //return add;
        return num1 + num2;
    }

    public double sub(double num1,double num2){
        //double sub = num1 - num2;
        //return sub;
        return num1 - num2;
    }

    public double mul(double num1,double num2){
        //double mul = num1 * num2;
        //return mul;
        return num1 * num2;
    }

    public double div(double num1,double num2){
        //double div = num1 / num2;
        //return div;
        return num1 / num2;
    }
}

package Object;

import java.util.Scanner;

public class CalculatorTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Calculator reCalculator = new Calculator();
        Scanner Input = new Scanner(System.in);
        boolean flag=true; //布尔类型变量，只有true和false两个值
        double result = 0.0;
        String action="";
        String answer="";
        System.out.println("请输入第一个数：");
        reCalculator.num1 = Input.nextDouble();
        System.out.println("请输入运算符");
        action = Input.next();
        System.out.println("请输入第二个数：");
        reCalculator.num2 = Input.nextDouble();

        if(action.equals("+")){
            result = reCalculator.add(reCalculator.num1, reCalculator.num2);
            //System.out.println("和为：" + reCalculator.add(num1,num2));
        }else if(action.equals("-")){
            result = reCalculator.sub(reCalculator.num1, reCalculator.num2);
            //System.out.println("差为：" + reCalculator.sub(num1,num2));
        }else if(action.equals("*")){
            result = reCalculator.mul(reCalculator.num1, reCalculator.num2);
            //System.out.println("积为：" + reCalculator.mul(num1,num2));
        }else if(action.equals("/")){
            result = reCalculator.div(reCalculator.num1, reCalculator.num2);
            //System.out.println("商为：" + reCalculator.div(num1,num2));
        }

        while(flag){
            System.out.println("是否继续输入数！");
            answer= Input.next();
            if(answer.equals("yes")){
                System.out.println("请输入运算符！");
                action = Input.next();
                System.out.println("请输入运算数！");
                double num = Input.nextDouble();
                if(action.equals("+")){
                    result = result + num;
                }else if(action.equals("-")){
                    result = result - num;
                }else if(action.equals("*")){
                    result = result * num;
                }else if(action.equals("/")){
                    result = result / num;
                }
                flag = true;
            }else{
                flag = false;
                System.out.println("计算结果为：" + result);
                Input.close();
            }
        }
    }
}

运行结果：