四则运算

package 输入输出;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.BufferedReader;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.OutputStreamWriter;

import java.util.Random;
import java.util.Scanner;






public class Yunsuan {


public static void main(String[] args) {
        String simple[]= {"+","-","*","/"};
        int[]  answer=new int[100];
    for(int i=0;i<100;i++) {//产生30个题目
        int a=(int)(Math.random()*10);//产生1-10的随机数
        int b=(int)(Math.random()*10);
    
            
       int c=(int)(Math.random()*4);
       String str =a+simple[c]+b;//运算符的位置
            switch(c)
            {
            case 0:answer[i]=a+b;break;
            case 1:answer[i]=a-b;break;
            case 2:answer[i]=a*b;break;
            case 3:{if(b==0) {
                do{
                    b=(int)(Math.random()*10);
                }while(b==0);
                answer[i]=a/b;break;
                }
            else answer[i]=a/b;break;
            }
            }
    
        try {
            BufferedWriter output = new BufferedWriter(new FileWriter(new File("D:\\title.txt "),true));
            
            output.write(str+"=");
            output.write("\r\n");
            output.close(); 
            }

            catch (Exception e){//异常处理}

        }
            
    }



File file = new File("D:\\title.txt");
int i=0;

int score=0;
if(file.exists()){  
    try {  
        FileReader fileReader = new FileReader(file);  
        BufferedReader br = new BufferedReader(fileReader);  
        String lineContent = null;  
        while((lineContent = br.readLine())!=null){  
            System.out.println(lineContent); 
           
            Scanner input = new Scanner(System.in);
            int a=input.nextInt();
            
            if(a==answer[i]) {
                System.out.println("回答正确！");
                score++;
            }
            else
                {System.out.println("回答错误! 答案是"+answer[i]);}
             
            i++;
        }  
        br.close();  
        fileReader.close();  
        
    } catch (FileNotFoundException e1) {  
        System.out.println("no this file");//文件不存在抛异常  
        e1.printStackTrace();  
    } catch (IOException e1) {  
        System.out.println("io exception");  
        e1.printStackTrace();
        
    } 
} System.out.println("分数为："+score);
    
}
}

用时四节课，思路正确，主要就是语法有问题，第一点，随机数调用的有问题，第二点，没有写出存答案的case语句，第三点读取语句不熟悉，出现了问题，所以时间拖了很久