刚开始学习JAVA自己写了很简单的模拟计算器的程序出现很多问题希望大家帮忙改改!!
import *;
public class 模拟计算器
{
       static BufferedReader keyboard=new BufferedReader(new InputStreamReader(System.in));
       public static void main(String[] args)throws IOException
       {
          double a,b,c;
          String d;
          System.out.print("请输入第一个运算数字:");
          System.out.flush();
          a=Double.parseDouble(keyboard.readLine());
          System.out.println();
          System.out.print("请输入第二个运算数字:");
          System.out.flush();
          b=Double.parseDouble(keyboard.readLine());
          System.out.println();
          System.out.print("请输入运算符号:");
          System.out.flush();
          d=keyboard.readLine();
          if(a!=0&&d!="/")
          System.out.println(a+d+b);
          else
          System.out.println("除数不能为零");
       }
}