Filewriter 求解！！！！

import java.util.Scanner;
import java.io.*;

public class basicType {

    public static void main(String[] args) throws IOException {
        String s1,s2;
        s1="Hellow,how are you?";
        s2="Hellow,how are you?";
        if(s1.equals(s2))
            System.out.println(s1);
        long Long=99999;
        int sum=0,i;
        String s3=" ";
        Scanner input=new Scanner(System.in);
        System.out.println("输入一些整数 以0结束。");
        do
        {
            try{
            i=input.nextInt();
            }
        catch(Exception e)
        {
            s3=input.next();
            i=1;
            continue;
        }
            sum+=i;
        }while(i!=0);
        System.out.println(sum);
        
        File f1=new File("E:\\2010javazhw\\java编程文件目录\\test.txt");
        FileWriter fw=new FileWriter(f1,true);
        fw.write(sum);
        fw.write('f');
        fw.write(s1);
        fw.write(Long);
        fw.close();
        int k;
        long l_1;
        String st;
        char ch;
        FileReader fr=new FileReader(f1);
        k=fr.read();
        System.out.println(k);
        ch=(char)fr.read();
        System.out.print(ch);
        //st=fr.read();
        
        
        
    }

}

顺便问一下，为何 一定要抛出异常？详细点，谢谢，还有就是 Filereader 如何才能 读 一长串字符？


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