JavaFX - 并发和更新标签 [英] JavaFX - Concurrency and updating label

问题描述

我有这些代码段的问题。我想创建一个应用程序，只要按下切换按钮，它就常常在标签中显示随机化的值。这是我创建的，它的工作，但窗口后几秒钟是滞后可怕。

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?

这里是类的代码，它生成随机值：

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;
    }
}

这里是一段Controller代码，方法：

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();
                        }

                    }
                });
            }

推荐答案

线程通过连续调用 Platform.runLater 。实现此目标的最佳方法是使用 <$

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()));
    }
};

，然后在您的示例中调用计时器：

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();
               }
       });
}

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