最简单的你可以用 switch case实现
public class Calculator {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
//无限循环在此加入while(true)
try {
System.out.println("请输入第一个数");
int a = sc.nextInt();
System.out.println("请输入第二个数");
int b = sc.nextInt();
System.out.println("请输入运算符 + = * /");
String s = sc.next();
switch (s){
case "*":
System.out.println("两数相乘的结果为:" + (a * b));
break;
case "/":
System.out.println("两数相除的结果为:" + (a / b));
break;
case "+":
System.out.println("两数相加的结果为:" + (a + b));
break;
case "-":
System.out.println("两数相减的结果为:" + (a - b));
break;
default:
System.out.println("请输入正确的运算符");
break;
}
}catch (NumberFormatException e){
System.out.println("请输入数字");
}
}
}