java - 如何在 JavaFX 中更改孩子的顺序

Question

是否可以更改 JavaFX2 子列表中节点的顺序？我尝试过set()，Collections.swap()但是两者都IllegalArgumentException加入，Parent因为在某些时候子列表在两个位置包含相同的项目（当节点位于新位置并且尚未从旧位置移除时）。Parent 中有标记，JavaFX 在内部使用这些标记toFront()并toBack()防止异常，但是无法从外部访问它们。

java.lang.IllegalArgumentException: Children: duplicate children added: parent = HBox@1424bf0
    at javafx.scene.Parent$1.onProposedChange(Parent.java:307)
    at com.sun.javafx.collections.VetoableObservableList.set(VetoableObservableList.java:156)
    at com.sun.javafx.collections.ObservableListWrapper.set(ObservableListWrapper.java:281)
    at java.util.Collections.swap(Collections.java:532)

Answer 1

您可以通过以下方式在父母的孩子列表中移动孩子

childNode.toFront();
childNode.toBack();

Answer 2

ObservableList<Node> workingCollection = FXCollections.observableArrayList(pane.getChildren());
Collections.swap(workingCollection, 0, 1);
pane.getChildren().setAll(workingCollection);

参考这段代码：

package swapnode;

import java.util.Collection;
import java.util.Collections;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 *
 * @author reegan
 */
public class SwapNode extends Application {

    @Override
    public void start(Stage primaryStage) {
        VBox root = new VBox(20);
        /* Thid Part Swap Children of Node */
        Pane pane = view();
        ObservableList<Node> workingCollection = FXCollections.observableArrayList(pane.getChildren());
        Collections.swap(workingCollection, 0, 1);
        pane.getChildren().setAll(workingCollection);

        root.getChildren().addAll(view(),pane);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * The main() method is ignored in correctly deployed JavaFX application.
     * main() serves only as fallback in case the application can not be
     * launched through deployment artifacts, e.g., in IDEs with limited FX
     * support. NetBeans ignores main().
     *
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

    public Pane view() {
        HBox pane = new HBox(10);
        Button button = new Button("Hello");
        TextField field = new TextField("World");
        pane.getChildren().addAll(button,field);
        return pane;
    }
}