comparable问题求教？

先上代码
import java.util.*;
import java.io.*;

public class Jukebox3
{
** ArrayList songList = new ArrayList();**

public static void main(String[] args) {
    new Jukebox3().go();
}

public void go() {
    getSongs();
    System.out.println(songList);
    **Collections.sort(songList);**
    System.out.println(songList);
}

void getSongs() {
    try {
        String path="e:\\SongList.txt"; 
       File file = new File(path);
        BufferedReader reader = new BufferedReader(new FileReader(file));
        String line = null;
        while ((line = reader.readLine()) != null) {
            addSong(line);
        }
    } catch (Exception ex) { ex.printStackTrace(); }
}

void addSong(String lineToParse) {
    String[]tokens = lineToParse.split("/");
    Song nextSong=new Song(tokens[0],tokens[1],tokens[2],tokens[3]);
    songList.add(nextSong);
}

}

class Song implements ComparableTo{
String title;
String artist;
String rating;
String bpm;

Song(String t,String a,String r,String b){
    title=t;
    artist=a;
    rating=r;
    bpm=b;
}

** public int compareTo(Song s){
return title.compareTo(s.getTitle());
}**

public String getTitle(){
    return title;
}

public String getRating(){
    return rating;
}
public String getArtist(){
    return artist;
}
public String getBpm(){
    return bpm;
}

public String toString(){
    return title;
}

}

java照着例子做的，但是编译还是报错，提示：sort不适用，comparable不适用的2个错误，我觉得会出问题的几行加粗了。看了网上其他人的comparable 的例子，自己找不出问题所在。

求大神解答。谢谢啦！

http://www.cnblogs.com/gnuhpc/archive/2012/12/17/2822251.html

你是想比较歌曲的title，然后输出？？？，sort 比较的类型应该不对，你看看例子

扫了一眼就被难住了，ComparableTo是嘛？