compute.java

用JAVA编的一个计算器的小程序

import java.io.*;

public class Compute{
	
    public static void main(String[] args) {
        String str1=" "; 
        String str2=" ";
        String str3=" ";
 
        while(true){
           try{
        	     InputStreamReader ins=new  InputStreamReader(System.in);
        	     BufferedReader br=new BufferedReader(ins);
        	     str1=br.readLine();
               if(str1.equalsIgnoreCase("over")) break;      	
               str2=br.readLine();
               str3=br.readLine();   
              }catch (IOException ie){}
                if(str1.indexOf(".")==-1){
                   int y1=Integer.parseInt(str1);
                   int y2=Integer.parseInt(str3);
                   int a=0;
                  if(str2.equalsIgnoreCase("+"))a=1;
                  else if(str2.equalsIgnoreCase("-"))a=2;
                  else if(str2.equalsIgnoreCase("*"))a=3;
                  else if(str2.equalsIgnoreCase("/"))a=4;
                   int y=0;
                   switch(a){
                     case 1:                    
                         y=y1+y2; 
                         break;
                     case 2:
                         y=y1-y2; 
                         break;
                     case 3:
                         y=y1*y2; 
                         break;
                     case 4:
                         y=y1/y2;
                         break;
                     default: break;
                    }//end switch
                   if(a!=1&&a!=2&&a!=3&&a!=4) {
                     	  System.out.println("The input is error!please intput again:");
                     	  System.out.println();
                    }else{
                        System.out.println("the result is: "+y);
                        System.out.println();
                      }
                  }else{
                    double y1=Double.parseDouble(str1);
                    double y2=Double.parseDouble(str3);
                    int a=0;
                    if(str2.equalsIgnoreCase("+"))a=1;
                     else if(str2.equalsIgnoreCase("-"))a=2;
                     else if(str2.equalsIgnoreCase("*"))a=3;
                     else if(str2.equalsIgnoreCase("/"))a=4;
                    double y=0;
                    switch(a){
                       case 1:
                         y=y1+y2;
                         break;
                       case 2:
                         y=y1-y2; 
                         break;
                       case 3:
                         y=y1*y2; 
                         break;
                       case 4:
                          y=y1/y2;
                         break;
                       default: break;
                      }//end switch
                      if(a!=1&&a!=2&&a!=3&&a!=4) {
                     	  System.out.println("The input is error!please intput again:");
                     	  System.out.println();
                      }else{
                        System.out.println("the result is: "+y);
                        System.out.println();
                       }
                    }//end else
            }//end while
      } 
   }