使用子列表获取错误

Question

我正在制作一个4人团队游戏，并被要求使用子列表。以下是清单：

/**
 * The list of players in this team.
 */
private final static List<Player> players = new LinkedList<Player>();

/**
 * A list of players in the waiting room.
 */
private final static List<Player> waitingPlayers = new LinkedList<Player>();

我收到了这个错误：

java.util.ConcurrentModificationException
[11/25/11 3:36 PM]:     at java.util.SubList.checkForComodification(Unknown Sour
ce)
[11/25/11 3:36 PM]:     at java.util.SubList.listIterator(Unknown Source)
[11/25/11 3:36 PM]:     at java.util.AbstractList.listIterator(Unknown Source)
[11/25/11 3:36 PM]:     at java.util.SubList.iterator(Unknown Source)
[11/25/11 3:36 PM]:     at java.util.AbstractCollection.contains(Unknown Source)

[11/25/11 3:36 PM]:     at java.util.AbstractCollection.removeAll(Unknown Source)

此处列出的代码。

public static void enterGame(final Client c) {      
    if(waitingPlayers.size() < 4) {
        c.sendMessage("Waiting for 4 players");
        return; // not enough players
    }
    // Picks 4 ppl from the list
    System.out.println("Starting new game");
    Collections.shuffle(waitingPlayers);
    System.out.println("Picking random players");
    final List<Player> picked = waitingPlayers.subList(0, 4); 
    players.addAll(picked);
    waitingPlayers.removeAll(picked);
    if(players.contains(c)) {
        c.sendMessage("Your on a team!");
    }
}

Answer 1

当基础原始列表更改时，subList变为无效。复制一份，例如使用

List<Player> picked = new ArrayList<Player>(waitingPlayers.subList(0,4));
waitingPlayers.removeAll(picked);