WebCAT爲（弗吉尼亞理工大學）提交將不會允許我提交此

Question

有人可以告訴我這是怎麼回事？這就是webcat所說的！

[PL10]在PlayList.removeSong（1）用3首歌曲： 播放列表removeSong [PL11]在PlayList.removeSong後具有錯誤的內容（2）與三首歌曲：播放列表removeSong [PL12後具有錯誤的內容] PlayList.removeSong（int）中有3首歌曲：播放列表在播放列表中應該保持不變，並且索引不良 [PL13] PlayList在播放歌曲後發生錯誤的內容（歌曲）> 1次 [PL14]異常調用播放列表.removeSong（Song）with 3首歌曲列表

import java.io.File; 
import java.util.ArrayList; 
import java.util.Scanner; 

public class PlayList { 
private String name; 
private ArrayList<Song> songList; 

public String getName() { 
    return this.name; 
} 

public String setName(String name) { 
    return this.name = name; 
} 

public ArrayList getsongList() { 
    return this.songList; 
} 

public ArrayList setsongList(ArrayList songList) { 
    return this.songList = songList; 
} 

@Override 
public String toString() { 
    return "PlayList [name= " + name + ", Songlist = " + songList + "]"; 
} 

public PlayList() { 
    this.name = "Untitled"; 
} 

public PlayList(String newName) { 
    this.name = newName; 
    songList = new ArrayList<Song>(); // add for both constructors 
} 

/** 
* Longest method. Takes input from file, converts it to string and displays 
* song or 'loads' it 
**/ 
public boolean loadSongs(String filename) { 
    try { 
     File text = new File(filename); 
     Scanner scan = new Scanner(text); 
     while (scan.hasNextLine()) { 
      String art = "anything"; 
      String sng = "somethingelse"; 

      for (int i = 0; i <= 4; i++) { 
       if (i == 0) { 
        art = scan.nextLine().trim(); 
        if (art.length() == 0) { 
         continue; 
        } 

       } 
       if (i == 1) { 
        sng = scan.nextLine(); 
       } 
       if (i == 2) { 
        String[] duration = scan.nextLine().split(";"); 
        int m = Integer.parseInt(duration[0]); // like 1: 
        int s = Integer.parseInt(duration[1]); // like 135 
        int sec = 0; 
        int min = 0; 
        int rem = 0; 
        if (s >= 60) { // if s = 135 
         sec = s/60; // sec = 2.25, or 2 
         rem = s % 60; // rem = 15 
         s = rem; // s is now 15 
         min = m * sec + m; // 1*2 + 1 = 3 
        } 

        Song anysong = new Song(art, sng, min, s); 
        songList.add(anysong); 

       } 

      } 

     } 

     return true; 
    } catch (Exception e) { 
     return false; 
    } 
} 

public boolean clear() { 

    if (!songList.isEmpty()) { 
     songList.clear(); 
     return true; 
    } 

    return false; 
} 

public boolean addSong(Song s) { 
    if (songList.add(s)) { 
     return true; 

    } 
    return false; 
} 

public Song removeSong(int index) { 
    index = 0; 
    int i = 0; 
    // check to see if the index is in the boundaries of the songList 
    if (index >= 0 && index < songList.size()) { 
     for (i = 0; i < songList.size(); i++) { 
      return songList.remove(i); 
     } 
     return songList.remove(i); 
    } 

    else { 
     return null; 
    } 

    // else return null 
    // if (index >= 0 && index < songList.size() 

} 

public Song removeSong(Song s) { 
    boolean found = false; 
    for (int j = 0; j > songList.size(); j++) { 
     songList.remove(s); 
     if (songList.remove(j).equals(songList.remove(j + 1))) { 
      found = true; 
      return s; 
     } else { 
      return null; 
     } 
     // compare all of these .equals() 
     // what your doing right now is deleting all the songs 
     // if you find that two are true, set ffound = true 
     // then return s if found is true, return null if found is false 
    } 
    return s; 
} 

// getSong method 

public Song getSong(int index) { 
    int i = 0; 
    if (index >= 0 && index <= songList.size()) { 
     for (i = 0; i < songList.size(); i++) { 
      return songList.get(i); 
     } 
    } 
    return songList.get(i); 
} 

// it is similar to the removeSong(int Index) 
// you need the same if statement 

public void play(Song s) { 
    for (int z = 0; z > songList.size(); z++) { 
     System.out.println(songList); 
    } 
} 

public int size() { 
    return songList.size(); 
} 

}

Answer 1

這是您的問題：

public ArrayList setsongList(ArrayList songList) { 
    return this.songList = songList; 
} 

這被接受和而場this.songList是ArrayList<Song>返回原始類型的ArrayList。這是一個很大的禁忌。修改代碼以將參數化類型作爲參數，並返回參數化類型。

修訂版

public ArrayList<Song> setsongList(ArrayList<Song> songList) { 
    return this.songList = songList; 
}