AnimationTimerのサンプル

AnimationDemo.java

import java.util.List;
import java.util.Random;
import java.util.stream.Collectors;
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class AnimationDemo extends Application {

    private long previous = 0;
    private final Random random = new Random();

    private static final double WIDTH = 600;
    private static final double HEIGHT = 400;

    @Override
    public void start(Stage stage) throws Exception {
        Pane root = new Pane();
        Scene scene = new Scene(root, WIDTH, HEIGHT);
        scene.setFill(Color.BLACK);

        stage.setScene(scene);
        stage.show();

        startAnimation(root);
    }

    private void startAnimation(Pane root) {
        AnimationTimer timer = new AnimationTimer() {
            @Override
            public void handle(long t) {
                if (previous == 0) {
                    previous = t;
                }

                // 適当なタイミングで四角を生成
                if (random.nextDouble() < 0.02) {
                    Rectangle rect = new Rectangle(WIDTH, random.nextDouble() * HEIGHT, 20, 20);
                    rect.setFill(Color.WHITE);
                    root.getChildren().add(rect);
                }

                // 四角を移動
                // 左側まで移動したら削除候補とする
                List<Node> removedRects
                        = root.getChildren().stream()
                                .map(node -> (Rectangle) node)
                                .map(rect -> {
                                    double x = rect.getX();
                                    x -= (t - previous) / 10_000_000.0;
                                    rect.setX(x);
                                    
                                    double y = rect.getY();
                                    y += random.nextDouble() * 2.0 - 1.0;
                                    rect.setY(y);
                                    
                                    return rect;
                                })
                                .filter(rect -> {
                                    double x = rect.getX();
                                    
                                    if (x < -WIDTH) {
                                        return true;
                                    } else {
                                        return false;
                                    }
                                })
                                .collect(Collectors.toList());
                
                // 左まで移動した四角を削除
                root.getChildren().removeAll(removedRects);
                
                previous = t;
            }
        };

        timer.start();
    }

    public static void main(String... args) {
        launch(args);
    }
}