这个程序是哪里不对？

//对元素为String的list进行排序。import java.io.BufferedReader;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.IOException;import java.io.PrintWriter;import java.util.*;class ComparatorString implements Comparator<Object>{    public int compare(Object arg0, Object arg1) {     String s0=(String)arg0;     String s1=(String)arg1;     int flag = s0.compareTo(s1);      return flag;    }   }public class Test{  public static void main(String[] args) {List<String> list = new ArrayList<String>();ComparatorString cs = new ComparatorString();try {BufferedReader is = new BufferedReader(new FileReader("god.txt"));String s;while((s=is.readLine())!= null){list.add(s);}Collections.sort(list,cs);is.close();PrintWriter w = new PrintWriter("sort.txt");for(String line : list)    w.println(line);        w.close();} catch (FileNotFoundException e) {System.out.println("没有找到god文件");} catch (IOException e) {System.out.println("发生了IO异常");}}}

? ? ?敬请指教！