使用 Java 实现一个简单计算器
在本程序中,您将学习使用 Java 中的 switch..case
制作一个简单的计算器。该计算器将能够对两个数字进行加、减、乘、除运算。
要理解此示例,您应该具备以下 Java 编程的知识:
- Java switch 语句
- Java Scanner 类
示例:使用 Java switch 语句的简单计算器
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
char operator;
Double number1, number2, result;
// create an object of Scanner class
Scanner input = new Scanner(System.in);
// ask users to enter operator
System.out.println("Choose an operator: +, -, *, or /");
operator = input.next().charAt(0);
// ask users to enter numbers
System.out.println("Enter first number");
number1 = input.nextDouble();
System.out.println("Enter second number");
number2 = input.nextDouble();
switch (operator) {
// performs addition between numbers
case '+':
result = number1 + number2;
System.out.println(number1 + " + " + number2 + " = " + result);
break;
// performs subtraction between numbers
case '-':
result = number1 - number2;
System.out.println(number1 + " - " + number2 + " = " + result);
break;
// performs multiplication between numbers
case '*':
result = number1 * number2;
System.out.println(number1 + " * " + number2 + " = " + result);
break;
// performs division between numbers
case '/':
result = number1 / number2;
System.out.println(number1 + " / " + number2 + " = " + result);
break;
default:
System.out.println("Invalid operator!");
break;
}
input.close();
}
}
输出 1
Choose an operator: +, -, *, or /
*
Enter first number
3
Enter second number
9
3.0 * 9.0 = 27.
在这里,我们使用 Scanner
该类从用户那里获取 3 个输入。
operator
- 指定要执行的操作number1
和number2
- 要对其执行操作的操作数
由于运算符匹配 case '*'
,因此执行相应的代码。
result = number1 * number2;
System.out.println(number + " * " + number2 + " = " + result);
break;
这些语句计算两个数字的乘积并打印输出。最后,break 语句结束 switch 语句。
同理,对于不同的算子,执行不同的 case。
输出 2
Choose an operator: +, -, *, or /
+
Enter first number
21
Enter second number
8
21.0 + 8.0 = 29.0
输出 3
Choose an operator: +, -, *, or /
-
Enter first number
9
Enter second number
3
9.0 - 3.0 = 6.0
输出 4
Choose an operator: +, -, *, or /
/
Enter first number
24
Enter second number
8
24.0 / 8.0 = 3.0