Java ObjectOutputStream / Objectinpustream - 对象只会发送一次

Question

我使用ObjectStreams在服务器和客户端之间进行通信。一切都很好。但现在我到了一个点，我想将ArrayList发送到客户端。类卡是可序列化的。

如果我第一次将ArrayList发送到客户端，则客户端从服务器发送ArrayList。

如果我更改Serverside上的ArrayList并将其发送到客户端，则客户端仍会获得旧版本。

以下是我使用的Codesnippets：

###Server###

for ( CardPlayer cp: players_in_game){
        cp.setHand(new ArrayList<Card>(0));
        System.out.println("Generate an empty ArrayList of Cards for : " + cp.getName() );
        cp.getHand().add(deck.takeCardFromTop()); 
        System.out.println("Add a card to hand of Player : " + cp.getName());
        cp.getHand().add(deck.takeCardFromTop());
        System.out.println("Add a card to hand of Player : " + cp.getName());
        cp.getHand().add(deck.takeCardFromTop());
        System.out.println("Add a card to hand of Player : " + cp.getName());
    }


    for ( CardPlayer cp: players_in_game ){

        String cmd = "updatecards";

        try {
            cp.getOos().writeObject(cmd);
            cp.getOos().flush();
            cp.getOos().writeObject(cp.getHand());
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }




    for ( CardPlayer cp: players_in_game){


        cp.getHand().add(deck.takeCardFromTop()); 
        System.out.println("Add a card to hand of Player : " + cp.getName());
        cp.getHand().add(deck.takeCardFromTop());
        System.out.println("Add a card to hand of Player : " + cp.getName());

    }


for ( CardPlayer cp: players_in_game ){

        String cmd = "updatecards";

        try {
            cp.getOos().writeObject(cmd);
            cp.getOos().flush();
            System.out.println("Server is sending an ArrayList with "+ cp.getHand().size() +" Cards");
            cp.getOos().writeObject(cp.getHand());
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }





###Client###

        while (gameIsStillActive) {

            String cmd = (String) ois_game.readObject();

            if (cmd.equals("updatecards")) {
                ArrayList recievedCards = (ArrayList) ois_game.readObject();

                System.out.println(this.name + ": Recieved a ArrayList with  " + recievedCards.size() + " Cards.");

            }

        }

 ###console###  
 Generate an empty ArrayList of Cards for : Harald
Add a card to hand of Player : Harald
Add a card to hand of Player : Harald
Add a card to hand of Player : Harald
Generate an empty ArrayList of Cards for : Stephan
Add a card to hand of Player : Stephan
Add a card to hand of Player : Stephan
Add a card to hand of Player : Stephan
Generate an empty ArrayList of Cards for : Dummy
Add a card to hand of Player : Dummy
Add a card to hand of Player : Dummy
Add a card to hand of Player : Dummy
Harald: Recieved a ArrayList with  3 Cards.
Stephan: Recieved a ArrayList with  3 Cards.
Dummy: Recieved a ArrayList with  3 Cards.
Add a card to hand of Player : Harald
Add a card to hand of Player : Harald
Add a card to hand of Player : Stephan
Add a card to hand of Player : Stephan
Add a card to hand of Player : Dummy
Add a card to hand of Player : Dummy
Server is sending an ArrayList with 5 Cards
Harald: Recieved a ArrayList with  3 Cards.
Server is sending an ArrayList with 5 Cards
Stephan: Recieved a ArrayList with  3 Cards.
Server is sending an ArrayList with 5 Cards
Dummy: Recieved a ArrayList with  3 Cards.
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