缓冲流四则运算

package bao;

/*import java.util.*;
import java.io.*;*/
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;
import java.util.Scanner;

public class hclszys {
    

    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入要生成的题目数量：");
        int num = sc.nextInt();

        int number1;
        int number2;
        int symbol;  

        File file = new File("E:\\Eclipse\\java作业\\huanchongliusizeyunsuan\\Text.txt"); //写入目标文件
        try {

        FileWriter fw = new FileWriter(file);

        BufferedWriter bw = new BufferedWriter(fw);

          
        
        for(int i=1;i<=num;i++)
        {
            number1 = new Random().nextInt(100);
            number2 = new Random().nextInt(100);
            symbol = new Random().nextInt(4);
            double answer = 0;
            while(number2 == 0)
                number2 = new Random().nextInt(100);
            bw.write(i + "、 " + number1);
            switch(symbol) {
            case 0:bw.write(" + ");answer = number1 + number2;break;
            case 1:bw.write(" - ");answer = number1 - number2;break;
            case 2:bw.write(" × ");answer = number1 * number2;break;
            case 3:bw.write(" ÷ ");
            answer = (double)Math.round((double)number1/(double)number2*100)/100;
            break;
            }

            bw.write(number2 + " = " + answer);
            bw.newLine();
            bw.write("***************************");
            bw.newLine();
            bw.flush();
        }

        bw.close(); //从上层数据关流

        /*fw.close();*/
        
        FileReader fr = new FileReader(file);
        BufferedReader br = new BufferedReader(fr);
        Scanner sc1 = new Scanner(System.in);
        int all = 0, count = 0;
        String t = "";
        double result;
        String str;
        while((str = br.readLine()) != null) {
            if(str.charAt(0)=='*'){            
                System.out.println("请输入答案");
                Scanner an=new Scanner(System.in);
               char putAnswer = an.next().charAt(0);
               char[] answers = null;
            int i = 0;
            if(putAnswer==answers[i]){
                int rightAnswer = 0;
                rightAnswer++;
               }
               i++;
            }
            all++;
            String[] a = str.split(" ");
            System.out.print(a[0] + a[1] + a[2] + a[3] + "=");
            result = sc1.nextDouble();
            if(result == Integer.parseInt(a[5]))
                count ++;
            else
                t += a[0];
            str = br.readLine();
            System.out.println(str);
        }
        br.close();
        System.out.println("共有" + all + "道题，做对了" + count + "道。");
        if(t != "")
            System.out.println("做错的题有：" + t.substring(0, t.length()));


        } catch (IOException e) {

        e.printStackTrace();

        }


        
        
    }

}