JavaFx：8、Group容器的使用

package fx.com;

import javafx.application.Application;
import javafx.collections.ListChangeListener;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.stage.Stage;



public class Main extends Application {
    public static void main(String[] args) {
        launch(args);
    }
    @Override
    public void start(Stage primaryStage) throws Exception {
        Button b1 = new Button("b1");
        b1.setLayoutX(100);
        b1.setLayoutY(100);
        b1.setPrefWidth(50);
        b1.setPrefHeight(50);

        Button b2 = new Button("b2");
        b2.setLayoutX(200);
        b2.setLayoutY(100);
        b2.setPrefWidth(50);
        b2.setPrefHeight(50);

        Button b3 = new Button("b3");
        b3.setLayoutX(300);
        b3.setLayoutY(100);
        b3.setPrefWidth(50);
        b3.setPrefHeight(50);

        Group group = new Group();
//        group.getChildren().add(b1);
//        group.getChildren().add(b2);
//        group.getChildren().add(b3);

        group.getChildren().addAll(b1,b2,b3);

        group.getChildren().addListener((ListChangeListener<Node>) c -> System.out.println("当前子组件数量="+c.getList().size()));
        b1.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                Button b4 = new Button("b4");
                group.getChildren().add(b4);
            }
        });

        Object[] objects = group.getChildren().toArray();
        for (Object o : objects){
            Button button = (Button) o;
            button.setPrefHeight(20);
            button.setPrefWidth(40);

        }

        Scene scene = new Scene(group);
        primaryStage.setScene(scene);
        primaryStage.setHeight(600);
        primaryStage.setWidth(800);
        primaryStage.show();
        primaryStage.centerOnScreen();
    }
}