import java.lang.ref.WeakReference;
import java.util.Collection;
import java.util.concurrent.CopyOnWriteArrayList;

import javax.swing.JPanel;
import javax.swing.SwingUtilities;

import javafx.application.Application;
import javafx.embed.swing.SwingNode;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;


public class LeakDemo extends Application {

    //Keep week references to all panels that we've ever generated to see if any
    //of them get collected.
    private Collection<WeakReference<JPanel>> panels = new CopyOnWriteArrayList<>();
    
    @Override
    public void start(Stage primaryStage) throws Exception {
        
        SwingNode node = new SwingNode();
        
        Pane root = new Pane();
        root.getChildren().add(node);
        
        //Kick off a thread that repeatedly creates new JPanels and resets the swing node's content
        new Thread(() -> {
            
            while(true) {
                
                //Lets throw in a little sleep so we can read the output
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                
                SwingUtilities.invokeLater(() -> {
                    JPanel panel = new JPanel();
                    panels.add(new WeakReference<>(panel));
                    node.setContent(panel);
                });
                
                System.out.println("Panels in memory: " + panels.stream().filter(ref -> ref.get() != null).count());
                
                //I know this doesn't guarantee anything, but prompting a GC gives me more confidence that this
                //truly is a bug.
                System.gc();
            }
            
        }).start();
        
        primaryStage.setScene(new Scene(root, 100, 100));
        
        primaryStage.show();
        
    }
    
    public static void main(String[] args) {
        launch(args);
    }
}