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！