我正在编写一个简单的音乐数据库和 ATM 我正在尝试创建一个播放列表类，它可以让用户将他们的音乐（先前输入数据库类的 4 首曲目）组织成 3 首歌曲的播放列表。
在用户选择要放入播放列表的歌曲后，该方法旨在搜索新播放列表中最近的空闲位置，并将歌曲变量（艺术家、名称、持续时间和文件大小）放入其中。
目前我收到这个；
进入播放列表工具...
您好，欢迎来到播放列表生成器！
请从下面的数据库中选择要添加到新播放列表的曲目（使用键 1-4）
插槽 1：树木：微风：2.34:128
1
错误：数据库中没有可用空间
插槽A：歌曲@3a1ec6
槽B：歌曲@1ba6076
槽 C : 歌曲@112e7f7
菜单
0 退出
1个进口轨道
2 显示全部
3 建立一个播放列表（需要数据库中至少 1 首曲目）
我是否正确猜测返回的是对变量位置的引用而不是变量本身？
Playlist.class 的代码是；
public class Playlist {
Song songDataPlay = new Song();
static UserInterface UI = new UserInterface();
static Song playlisttrackA = new Song();
static Song playlisttrackB = new Song();
static Song playlisttrackC = new Song();
private int MAX_TIME;
private double totalSize;
private double totalTIme;
String playlistClassArtist, playlistClassName;
double playlistClassDuration;
int playlistClassFileSize;
static String playlistArtist;
static String playlistName;
static double playlistDuration;
static int playlistFileSize;
static Song newplaySong;
static Song newSong;
static Song carryfromuserintoplaylist = UI.newPlaylistSongIN;
public void playlistObject(Song a, Song b, Song c) {
this.playlisttrackA = a;
this.playlisttrackB = b;
this.playlisttrackC = c;
}
public static void playlistAllocation() {
newSong = UI.newPlaylistSongIN;
Playlist plu = new Playlist();
SongDatabase SD = new SongDatabase();
Song newSong = carryfromuserintoplaylist;
if (playlisttrackA.songfileSize == 0) {
setSongA(newplaySong);
System.out.println("Slot A : " + playlisttrackA);
System.out.println("Slot B : " + playlisttrackB);
System.out.println("Slot C : " + playlisttrackC);
newplaySong = newSong;
} else if (playlisttrackB.songfileSize == 0) {
setSongB(newplaySong);
System.out.println("Slot A : " + playlisttrackA);
System.out.println("Slot B : " + playlisttrackB);
System.out.println("Slot C : " + playlisttrackC);
newplaySong = newSong;
} else if (playlisttrackC.songfileSize == 0) {
setSongC(newplaySong);
System.out.println("Slot A : " + playlisttrackA);
System.out.println("Slot B : " + playlisttrackB);
System.out.println("Slot C : " + playlisttrackC);
newplaySong = newSong;
} else {
System.out.println("Error: there is no free space in the database");
System.out.println("Slot A : " + playlisttrackA);
System.out.println("Slot B : " + playlisttrackB);
System.out.println("Slot C : " + playlisttrackC);
}
}
public static void setSongA(Song newSong) {
playlisttrackA = newplaySong;
playlisttrackA.songartist = newplaySong.songartist;
playlisttrackA.songname = newplaySong.songname;
playlisttrackA.songduration = newplaySong.songduration;
playlisttrackA.songfileSize = newplaySong.songfileSize;
}
public Song getSongA() {
return (playlisttrackA);
}
public static void setSongB(Song newSong) {
playlisttrackB = newplaySong;
playlisttrackB.songartist = newplaySong.songartist;
playlisttrackB.songname = newplaySong.songname;
playlisttrackB.songduration = newplaySong.songduration;
playlisttrackB.songfileSize = newplaySong.songfileSize;
}
public Song getSongB() {
return (playlisttrackB);
}
public static void setSongC(Song newSongC) {
playlisttrackC = newplaySong;
playlisttrackC.songartist = newplaySong.songartist;
playlisttrackC.songname = newplaySong.songname;
playlisttrackC.songduration = newplaySong.songduration;
playlisttrackC.songfileSize = newplaySong.songfileSize;
}
public Song getSongC() {
return (playlisttrackC);
}
public String returnPlaylist() {
if (playlisttrackA.songfileSize == 0 && playlisttrackB.songfileSize == 0 && playlisttrackC.songfileSize == 0) {
return ("Error ; No new playlists have been added.");
} else if (playlisttrackB.songfileSize == 0 && playlisttrackC.songfileSize == 0) {
return ("You have imported:" + newplaySong.songname + " By " + newplaySong.songartist + " to slot A in the new playlist");
} else if (newplaySong.songfileSize == 0) {
return ("You have imported:" + newplaySong.songname + " By " + newplaySong.songartist + " to slot B in the new playlist");
} else {
return ("You have imported:" + newplaySong.songname + " By " + newplaySong.songartist + " to slot C in the new playlist");
}
}
}
任何帮助都会非常感谢，