Open card after certain time

问题

i'm programming a blackjack (single thread) for a university project and the dealer is the computer (e.g. no player action)...

Does someone know how can I program in Java something like this:

while (dealerpoints < 17)
    open card and repaint frame
    wait 1 sec (to run again the condition test for while)

THe thing is, I don't want all dealer cards painted at once...

Thanks in advance, Gabriel Sotero

UPDATE: this is my code (that doesn't work)

        while (Dealer.getInstance().dealerPoints < 17){

            Dealer.getInstance().openCard();
            try {
                Thread.sleep(100);
            }
            catch (InterruptedException e){ }
        }

openCard declaration:

    private void openCard(){

        Card temp;

        temp = Deck.getInstance().myPop();
        Dealer.getInstance().cards.add(temp);
        Dealer.getInstance().dealerPoints += temp.getValue(); 
        MainPanel.getInstance().updateDealerLabel(Dealer.getInstance().dealerPoints);
        MainPanel.getInstance().repaint();

    }

回答1:

You can't block the Event Dispatching Thread as it is responsible for (amongst other things) processing re-paint requests. So all the time you're waiting, the UI is not begin updated. This includes using loops and Thread#sleep.

One solution is to use a SwingWorker, but, it's unreliable in terms of when it will call an update back to the UI.

The other solution would be to use a javax.swing.Timer which will trigger a call back every n periods and is executed within the Event Dispatching Thread...

Something like...

Timer dealerTimer= new Timer(1000, new ActionListener() {
    public void actionListener(ActionEvent evt) {
        if (Dealer.getInstance().dealerPoints < 17) {
            Dealer.getInstance().openCard();
        } else {
            ((Timer)evt.getSource()).stop();
        }
    }
});
dealerTimer.setRepeats(true);
dealerTimer.start();

What I would do, is declare dealerTimer as a class field. When required, I would simply call dealerTimer.restart() to get the timer to restart. You might also want to check dealerTimer.isRunning() to make sure that the timer isn't already running ;)

You might like to have a read through Concurrency in Swing for some more information

回答2:

You could use: http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Thread.html#sleep(long). Put it in a try-except block.

// To wait 1 second:
try {
    Thread.sleep(1000);
} catch (Exception e) {}

回答3:

go to sleep for a bit

try {
    Thread.sleep(1000);
}catch (InterruptedException e){
   LOG.warning("unexpected interruption while sleeping");
}

来源：https://stackoverflow.com/questions/13617871/open-card-after-certain-time

标签

java

swing

concurrency

event-dispatch-thread