java实现计算器代码怎么写

以下是一个简单的Java计算器代码示例：

import java.util.Scanner;  public class Calculator {     public static void main(String[] args) {         Scanner scanner = new Scanner(System.in);                  System.out.println("Enter the first number: ");         double num1 = scanner.nextDouble();                  System.out.println("Enter the second number: ");         double num2 = scanner.nextDouble();                  System.out.println("Enter the operation (+, -, *, /): ");         char operation = scanner.next().charAt(0);                  double result = 0;                  switch(operation) {             case '+':                 result = num1 + num2;                 break;             case '-':                 result = num1 - num2;                 break;             case '*':                 result = num1 * num2;                 break;             case '/':                 result = num1 / num2;                 break;             default:                 System.out.println("Invalid operation.");         }                  System.out.println("Result: " + result);                  scanner.close();     } } 

此代码通过用户输入两个数和运算符，然后根据运算符执行相应的运算，最终输出结果。您可以根据自己的需求对此代码进行修改和扩展。