练习题：计算器（只输入两个数运算）

CV：

import java.util.Scanner;

public class Test01 {
public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

while (true){
System.out.println("开始计算请按Y,关闭请按N");
String a = scanner.next();

if (a.equals("Y")){
System.out.println("请输入第一个数：");
float num1 = scanner.nextFloat();

System.out.println("请输入运算符：");
String operator = scanner.next();

System.out.println("请输入第二个数：");
float num2 = scanner.nextFloat();

switch (operator){
case "+":
add(num1,num2);
break;
case "-":
minus(num1,num2);
break;
case "":
multiply(num1,num2);
break;
case "/":
divide(num1,num2);
break;
}
}else {
System.out.println("关闭");
break;
}
}
scanner.close();
}
public static void add(float a,float b){
System.out.println("a+b="+(a+b));
}
public static void minus(float a,float b){
System.out.println("a-b="+(a-b));
}
public static void multiply(float a,float b){
System.out.println("ab="+(a*b));
}
public static void divide(float a,float b){
System.out.println("a/b="+(a/b));
}

}