JavaFX - Concurrency and updating label

问题

I've got problem with these piece of code. I want to make an application, which constatnly displays randomized values in labels as long as the Toggle Button is pressed. That's what I created, it works but window after a few seconds is lagging horrible. What am I doing wrong?

Here is code of class, which generate random values:

public class ValueMaker{
    private StringPropterty x, y, z;
    private Random generator;
    private boolean isStarted = false;
    private int randomizedX(){ return generator.nextInt(10); }
    private int randomizedY(){ return generator.nextInt(10); }
    private int randomizedZ(){ return generator.nextInt(10); }

    public StringProperty xProperty(){ return x; }
    public StringProperty yProperty(){ return y; }
    public StringProperty zProperty() { return z; }

    public ValueMaker(){
        x = new SimpleStringProperty("0");
        y = new SimpleStringProperty("0");
        z = new SimpleStringProperty("0");
        generator = new Random();
    }



    private void setValues(){
        Platform.runLater(new Runnable() {
            @Override
            public void run() {
                x.set(String.valueOf(randomizedX()));
                y.set(String.valueOf(randomizedY()));
                z.set(String.valueOf(randomizedZ()));
            }
        });
    }

    public startRandomize(){
        isStarted = true;
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                while (isStarted){
                    setValues();
                }
            }
        });
        t.start();
    }

    public stopRandomize(){
        isStarted = false;
    }
}

And here is piece of Controller code, which calls these methods:

   @FXML
   private void initialize(){
            labelX.textProperty().bind(ValueMaker.xProperty());
            labelY.textProperty().bind(ValueMaker.yProperty());
            labelZ.textProperty().bind(ValueMaker.zProperty());
            startRandomizeButton.selectedProperty().addListener(new ChangeListener<Boolean>() {
                    @Override
                    public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
                        if (newValue==true){
                            ValueMaker.startRandomize();
                        }
                        else{
                            ValueMaker.stopRandomize();
                        }

                    }
                });
            }

回答1:

You are jamming the JavaFX application thread by calling Platform.runLater continuously. The best way to achieve this would be to use a AnimationTimer which will be called in each frame while it is active.

AnimationTimer timer = new AnimationTimer() {    

    @Override
    public void handle(long now) {
        x.set(String.valueOf(randomizedX()));
        y.set(String.valueOf(randomizedY()));
        z.set(String.valueOf(randomizedZ()));
    }
};

and then call the timer in your example :

startRandomizeButton.selectedProperty().addListener(new ChangeListener<Boolean>() {
       @Override
       public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
               // newValue==true is not required
               if (newValue){
                   timer.start();
               }
               else{
                   timer.stop();
               }
       });
}

回答2:

I think when you start your thread - it uses all available resources. It works in an infinite loop and generates random numbers without taking a "break".
Try adding sleep to the thread's loop, so that it will be getting suspended for few milliseconds and releasing CPU a little.
You may need to add sleep anyway, otherwise the randomized labels will change too fast.

来源：https://stackoverflow.com/questions/29941093/javafx-concurrency-and-updating-label