大神们帮我看一下下面的程序有什么地方可以优化，并指出存在的问题

[黑夜中的一点慰藉]

大神们帮我优化一下下面的程序，并指出存在的问题，（将两个txt文件内容分别去重并去除重复内容后写入到另外两个txt文件，）

package com.wwy.io;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class CopyFile {

	/**
	 * @param args
	 */
	@SuppressWarnings("unchecked")
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		List<List> mylist = read();
		List<List> my = read();
		List<String> l1 = repetition(mylist.get(0), mylist.get(1));
		List<String> l2 = repetition(my.get(1),my.get(0));
		write(l1,l2);
		System.out.println("ok");
	}

	public static List<List> read(){
		File f1 = new File("D:\\a\\test1.txt");
		File f2 = new File("D:\\a\\test2.txt");
		List<List> mylist = new ArrayList<List>(); 
		List<String> l1 = new ArrayList<String>();
		List<String> l2 = new ArrayList<String>();
		String str1 = "";
		String str2 = "";
		BufferedReader br1 = null;
		BufferedReader br2 = null;
		try {
			br1 = new BufferedReader(new FileReader(f1));
			br2 = new BufferedReader(new FileReader(f2));
			while((str1 = br1.readLine() ) != null ){// (str2 = br2.readLine()) != null){
				l1.add(str1);
			}
			while((str2 = br2.readLine()) != null){
				l2.add(str2);
			}
			mylist.add(l1);
			mylist.add(l2);
				
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				if(br1 != null){
					br1.close();
					br1 = null;
				}
				if(br2 != null){
					br2.close();
					br2 = null;
				}
			} catch (Exception e2) {
				// TODO: handle exception
			}
		}
		return mylist;
	}
	
	public static List<String> repetition(List<String> l1,List<String> l2){
		for(int i = 0; i < l1.size(); i++){
			for(int j = 0;j<l2.size();j++){
				if(l2.get(j) .equals(l1.get(i))){
					System.out.println("sdgsad======" + l1.get(i));
					l1.remove(i);
				}
			}
			
		}
		/*for(String str1 :l1){
			System.out.println("str1 : " + str1);
			 for(String str2 : l2){
				 System.out.println("str2 : " + str2);
				 if(str1.equals(str2)){
					 System.out.println("222 2 " + str1);
					 //int index = l1.indexOf(str1);
					 l1.remove(str1);
					 System.out.println("============ " + l1.remove(str1) );
				 }
			 }
		}*/
		return l1;
	}
	
	public static void write(List<String> l1,List<String> l2){
		File f1 = new File("D:\\a\\result1.txt");
		File f2 = new File("D:\\a\\result2.txt");
		BufferedWriter bw1 = null;
		BufferedWriter bw2 = null;
		try {
			bw1 = new BufferedWriter(new FileWriter(f1));
			bw2 = new BufferedWriter(new FileWriter(f2));
			for(int i = 0;i < l1.size();i++){
				bw1.write(l1.get(i) + "\n");
			}
			for(int i = 0;i < l1.size();i++){
				bw2.write(l2.get(i) + "\n");
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				if(bw1 != null){
					bw1.close();
					bw1 = null;
				}
				if(bw2 != null){
					bw2.close();
					bw2 = null;
				}
			} catch (Exception e2) {
				// TODO: handle exception
			}
		}
	}
}

[Inhibitory]

    public static List<String> repetition(List<String> l1,List<String> l2){
        for(int i = 0; i < l1.size(); i++){
            for(int j = 0;j<l2.size();j++){
                if(l2.get(j) .equals(l1.get(i))){
                    System.out.println("sdgsad======" + l1.get(i));
                    l1.remove(i);
                }
            }
             
        }
        /*for(String str1 :l1){
            System.out.println("str1 : " + str1);
             for(String str2 : l2){
                 System.out.println("str2 : " + str2);
                 if(str1.equals(str2)){
                     System.out.println("222 2 " + str1);
                     //int index = l1.indexOf(str1);
                     l1.remove(str1);
                     System.out.println("============ " + l1.remove(str1) );
                 }
             }
        }*/
        return l1;
    }

去重复这一段代码可以直接用List.removeAll()方式，而不用自己重写

[黑夜中的一点慰藉]

引用 1 楼 Inhibitory 的回复:

Java code?123456789101112131415161718192021222324 public static List<String> repetition(List<String> l1,List<String> l2){ for(int i = 0; i < l1.size(); i++){ for(int ……

谢谢！以前没注意这个方法，这样确实简化了很多了，但是我更想知道了集合方面有没有优化的，感觉集合那部分运用太别扭了，集合是不是有修改记忆功能？？