java - 获取秒值并显示到控制台窗口

Question

我在 JavaFX 中编写了一个简单的倒数计时器，并通过绑定(bind)实现了计时器，因此每当 timeSeconds 的值发生变化时，timerLabel 文本也会发生变化。

如何获取当前秒数并将其显示到控制台窗口？输出应在每个新行显示当前秒数的值，如下所示:543210

public class FXTimerBinding extends Application
{
//  private class constant and somme variables
private static final Integer STARTTIME = 5;
private Timeline timeline;
private Label timerLabel = new Label();
private IntegerProperty timeSeconds = new SimpleIntegerProperty(STARTTIME);

@Override
public void start(Stage primaryStage)
{
    //  setup the Stage and the Scene(the scene graph)
    primaryStage.setTitle("FX Timer binding");
    Group root = new Group();
    Scene scene = new Scene(root, 300, 250);

    //  configure the label
    timerLabel.setText(timeSeconds.toString());
    timerLabel.setTextFill(Color.RED);
    timerLabel.setStyle("-fx-font-size: 4em;");

    // Bind the timerLabel text property to the timeSeconds property
    timerLabel.textProperty().bind(timeSeconds.asString());

    //  create and configure the Button
    Button button = new Button("Start timer");
    button.setOnAction(new EventHandler<ActionEvent>(){

        @Override
        public void handle(ActionEvent event)
        {
            if(timeline != null)
                timeline.stop();

            timeSeconds.set(STARTTIME);
            timeline = new Timeline();

            KeyValue keyValue = new KeyValue(timeSeconds, 0);
            KeyFrame keyFrame = new KeyFrame(Duration.seconds(STARTTIME + 1), keyValue);

            timeline.getKeyFrames().add(keyFrame);
            timeline.playFromStart();

     System.out.println("get every seconds value and display to console window");
        }
    });

来自:http://www.asgteach.com/blog/?p=334

Answer 1

如果您想在 timeSeconds 的实际值发生变化时执行其他操作，只需为其添加一个监听器即可:

timeSeconds.addListener((observable, oldTimeValue, newTimeValue) -> {
    // code to execute here...
    // e.g.
    System.out.println("Time left: "+newTimeValue);
});

但是，如果您要更改 UI 以响应倒计时更改值，那么最好使用已有的绑定(bind)，恕我直言。