用java的io流，将一个文本框的内容反转

import java.io.*;
import java.util.ArrayList;

public class test04 {
    public static void main(String args[]) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("xxx.txt"));
        BufferedWriter bw = new BufferedWriter(new FileWriter("yyy.txt"));

        ArrayList<String> list = new ArrayList<>();

        String line;
        while((line = br.readLine())!=null){
            list.add(line);
        }

        int i;
        for (i=list.size()-1;i>=0;i--){
            bw.write(list.get(i));
            bw.newLine();
        }

        br.close();
        bw.close();

    }
}