Question

倒计时不起作用。我通过一个按钮触发它。

public void startCountDown() {
    timer.schedule(new TimerTask() {
    @Override
        public void run() {
        Platform.runLater(new Runnable() {
           public void run() {
               countDown--;
                countDownText.setText("Time left:" + countDown);

                if (countDown < 0)
                    timer.cancel();
          }
        });
    }
    }, 1000); //Every 1 second
}

countDown变量设置为60，因此倒计时从60开始

编辑：倒计时卡在59秒，countDown是一个int。没有错误。 countDownText声明为文本。

@FXML
private Text countDownText;

Answer 1

有超过1个计时器类，但我假设您使用了java.util.Timer

检查API显示您使用了此方法：

public void schedule(TimerTask task,
            long delay)

Schedules the specified task for execution after the specified delay.

Parameters:
    task - task to be scheduled.
    delay - delay in milliseconds before task is to be executed.
Throws:
    IllegalArgumentException - if delay is negative, or delay + System.currentTimeMillis() is negative.
    IllegalStateException - if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated.
    NullPointerException - if task is null

所以你的程序等待1秒然后执行run（）方法，但不重复。要重复它，您需要使用此方法：

public void schedule(TimerTask task,
            long delay,
            long period)

Schedules the specified task for repeated fixed-delay execution, beginning after the specified delay. Subsequent executions take place at approximately regular intervals separated by the specified period.

In fixed-delay execution, each execution is scheduled relative to the actual execution time of the previous execution. If an execution is delayed for any reason (such as garbage collection or other background activity), subsequent executions will be delayed as well. In the long run, the frequency of execution will generally be slightly lower than the reciprocal of the specified period (assuming the system clock underlying Object.wait(long) is accurate).

Fixed-delay execution is appropriate for recurring activities that require "smoothness." In other words, it is appropriate for activities where it is more important to keep the frequency accurate in the short run than in the long run. This includes most animation tasks, such as blinking a cursor at regular intervals. It also includes tasks wherein regular activity is performed in response to human input, such as automatically repeating a character as long as a key is held down.

Parameters:
    task - task to be scheduled.
    delay - delay in milliseconds before task is to be executed.
    period - time in milliseconds between successive task executions.
Throws:
    IllegalArgumentException - if delay < 0, or delay + System.currentTimeMillis() < 0, or period <= 0
    IllegalStateException - if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated.
    NullPointerException - if task is null

您可以在此处查看完整的文档：http://docs.oracle.com/javase/7/docs/api/java/util/Timer.html#schedule%28java.util.TimerTask,%20long%29

以下是我认为正确的代码：

public void startCountDown() {
    timer.schedule(new TimerTask() {
    @Override
        public void run() {
        Platform.runLater(new Runnable() {
           public void run() {
               countDown--;
                countDownText.setText("Time left:" + countDown);

                if (countDown < 0)
                    timer.cancel();
          }
        });
    }
    }, 1000, 1000); //Every 1 second
}

JAVAFX，Countdown不起作用

1 个答案: