布尔值未在线程中更改

Question

我有一个MPClient和MultiplayerMatch类。MultiplayerMatch在其构造函数中创建一个MPClient可运行线程。

为了避免数据溢出，我在MultiplayerMatch中有一个名为“ moved”的布尔值，当播放器移动时，它会变为true。

在updateMatch方法中，如果有任何播放器移动，则“
moved”变为true，这允许MPClient输入if语句（在while内）。这样，MPClient仅在游戏发生更改时才将数据发送到服务器。

但是，当该标志为true时，则不会在MPClient中注册该更改！即使在MultiplayerMatch中更改了该标志，MPClient仍然“认为”移动等于假，结果没有任何内容发送到服务器…

经过几次测试后，我注意到如果以调试模式运行它，因为我有一些断点，则将记录该更改，并且一切正常！为什么通过调试模式只能“看到”布尔更改？由于存在断点，它是否与应用程序的“运行速度”有关？

这只是代码的重要部分：

MPClient：

public class MPClient {
static final int TIME_OUT = 5000;
Client client;
MultiPlayMatch match;

public MPClient(String name, int team, MultiPlayMatch match) {
    this.match = match;
    client = new Client();
    client.start();

    Network.registerPackets(client);
    addListeners();

    try {
        client.connect(TIME_OUT, "127.0.0.1", Network.PORT);
    } catch (IOException e) {
        e.printStackTrace();
        client.stop();
    }

    /*this comment is just to show that here is the place where the login information is sent to the server, instead of showing all the code*/

    PlayerInfo playerInfo = new PlayerInfo();
    Network.UpdatePlayer updatePlayer = new Network.UpdatePlayer();
    updatePlayer.name = name;
    updatePlayer.team = team;

    while(true) {
        if(match.moved) {       //--> this is the variable that is always false
            playerInfo.x = match.getClientPlayerX(team);
            playerInfo.y = match.getClientPlayerY(team);

            updatePlayer.x = playerInfo.x;
            updatePlayer.y = playerInfo.y;
            client.sendTCP(updatePlayer);
            match.moved = false;
        }
    }

}

private void addListeners() {
    client.addListener(new Listener.ThreadedListener(new Listener() {
        @Override
        public void received(Connection connection, Object object) {
            if(object instanceof Network.UpdatePlayer) {
                Network.UpdatePlayer updatePlayer = (Network.UpdatePlayer) object;
                match.setPlayerPosition(updatePlayer.x, updatePlayer.y, updatePlayer.name, updatePlayer.team);
            }
        }
    }));
}
}

多人比赛：

public class MultiPlayMatch extends Match {

public boolean moved;

public MultiPlayMatch(){
    super(0);

    Random r = new Random();
    int aux = r.nextInt(2);
    aux = 0;
    if(aux == 0){
        homeTeam = new Team("Benfica", Team.TeamState.Attacking, w);
        visitorTeam = new Team("Porto", Team.TeamState.Defending, w);
    } else{
        homeTeam = new Team("Benfica", Team.TeamState.Defending, w);
        visitorTeam = new Team("Porto", Team.TeamState.Attacking, w);
    }
    //homeTeam.controlPlayer(0);

    numberOfPlayers = 0;
    moved = false;
}

@Override
public void updateMatch(float x, float y, Rain rain, float dt) {
    homeTeam.updateControlledPlayerOnline(x, y);

    rain.update();
    w.step(Constants.GAME_SIMULATION_SPEED, 6, 2);

    if(x != 0 || y != 0) moved = true;      //this is the place the variable is changed, but if it isn't in debug mode, MPClient thinks it's always false
}

public void setPlayerPosition(float x, float y, String name, int team) {
    if(team == 0)
        homeTeam.changePlayerPosition(x, y, name);
    else
        visitorTeam.changePlayerPosition(x, y, name);
}
}

Answer 1

这是因为它正在读取match.moved变量的缓存值，而不是最新值。为了避免这种情况，请将变量声明为volatile

public volatile boolean moved;

在这里阅读更多