JavaFx，如何在樹表視圖中正確覆寫：getChildren()和getChildren().add(newNode)

在一個非常廣泛使用TreeTableViews的應用程式中，我遇到了每次將子項添加到這棵樹時都需要觸發代碼的情況。

我的第一種方法是“封裝”myTree.getChildren().add(...)方法內部，例如：

    public boolean addToChildren(TreeItemPlaylist tritPlaylist) {
        boolean resAdd = false;
        resAdd = getChildren().add(tritPlaylist);
        [... personalized code which might affect the resAdd ...]
        return resAdd;
    }

這仍然getChildren().add(...)可以訪問，因此可以繞過我的個性化代碼。

我正在尋找更清潔的東西，并且試圖覆寫該TreeTableView 中的add(newNode)方法getChildren()。

我做了很多研究，最后試圖做：

1. 一個平行的兒童串列。然后可以訪問
2. 有它的 'add(...) 覆寫
3. 而該名單由回傳getChildren()的TreeItem

的 Overriden 部分的getChildren()靈感來自

表現形式1：樹

所以在這兩種情況下，我的第一個孩子串列都存在......它們在根樹專案下，但是：當通過自定義的 ObservableList 時，它們沒有顯示在樹中，在根下。

據我所知，TreeTableView 的機制依賴于對 TreeItem 串列的特定呼叫：子項，可能我在那里遺漏了一些東西......因為我做了一個并行的 LIST，因此它不被稱為......有點。 ..做了一些研究和實驗，但到目前為止沒有運氣:-(。

是不是因為：

• There is something missing on the TreeTableView : CellValueFactory / CellFactory / TreeItems / ...
• There is something wrong about my ObservableList : Another override I should implement / Wrong ascendant used / Should 'implement' and 'extend' rather than 'extend' ?

Manifestation 2 : Children / Parent

I have broken the children/parent ! This also has to do with the fact that I tried to build a parallel LIST and made a customized getChildren(). Should be a customization of super.getChildren() I suppose, but then again, tried many ways without success. And if so, I don't get my customnized LIST but the original (correct) one.

Help would be greatly appreciated.

MCE :

package overrides;

import javafx.application.Application;
import javafx.beans.property.SimpleListProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableRow;
import javafx.scene.control.TreeTableView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class CustomedTypedTreeTableSample extends Application {

    public final class ObservableListOfTreeItemPlaylist<T> extends SimpleListProperty<T> {

        ObservableListOfTreeItemPlaylist() {
            super(FXCollections.observableArrayList());
        }

        @Override
        public boolean add(T element) {
            System.out.println("Adding an element");
            return super.add(element);
        }

    }

    public class TreeItemPlaylist extends TreeItem<TreeTableRowPlaylist> {

        private ObservableListOfTreeItemPlaylist<TreeItem<TreeTableRowPlaylist>> playlistItems = new ObservableListOfTreeItemPlaylist<>();

        public TreeItemPlaylist(TreeTableRowPlaylist treeTableRow) {
            super(treeTableRow);
        }

        ////////////////////////
        // COMMENT / UNCOMMENT the next overridden method to see my problem
        //
        // When commenting : - GUI tree is filled with the correct children. All is fine... but, of course, no customized 'add(...'
        // - When printing to console the children of root : All branches and children are there !
        //
        // When NOT commenting : - The overridden 'add(T element)' of class ObservableListOfTreeItemPlaylist is fired...
        // - GUI tree is left with only the ROOT element
        // - When printing to console only the first children of root are there ! But hey... they are there on the console, but not in the GUI !
        @Override
        public ObservableListOfTreeItemPlaylist<TreeItem<TreeTableRowPlaylist>> getChildren() {
            return playlistItems;
        }
        ////////////////////////
    }

    public class TreeTableRowPlaylist extends TreeTableRow<TreeTableRowPlaylist> {

        // Initialized during constructor
        private SimpleStringProperty name;

        public String getName() {
            return name.get();
        }

        public void setName(String name) {
            this.name.set(name);
        }

        public SimpleStringProperty nameProperty() {
            return name;
        }

        public TreeTableRowPlaylist(String name) {
            super();
            this.name = new SimpleStringProperty(name);
        }
    }

    @SuppressWarnings ("unchecked")
    @Override
    public void start(Stage primaryStage) {
        ///// TreeTableView basics
        // Tree table view
        TreeTableView<TreeTableRowPlaylist> tableView = new TreeTableView<>();
        // Column for the name
        TreeTableColumn<TreeTableRowPlaylist, String> nameColumn = new TreeTableColumn<>("Name");
        nameColumn.setCellValueFactory(param -> param.getValue().getValue().nameProperty());
        // Add column
        tableView.getColumns().addAll(nameColumn);

        ///// Dummy tree building
        tableView.setRoot(new TreeItemPlaylist(new TreeTableRowPlaylist("ROOT")));
        tableView.getRoot().getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf 1")));
        tableView.getRoot().getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf 2")));
        TreeItemPlaylist aTreeBranchA = new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Branch A"));
        aTreeBranchA.getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf A.1")));
        aTreeBranchA.getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf A.2")));
        tableView.getRoot().getChildren().add(aTreeBranchA);

        ///// Testing if overriding is working
        // button to get the list of children
        Button display = new Button("Print out children list to console");
        display.setOnAction(event -> tableView.getRoot().getChildren().forEach(playlist -> printChildrenToConsole(playlist)));

        ///// Setting the GUI
        VBox vbox = new VBox(0, tableView, display);

        Scene scene = new Scene(vbox);

        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void printChildrenToConsole(TreeItem<TreeTableRowPlaylist> playlist) {
        System.out.println(playlist.getValue().getName());
        if (!playlist.isLeaf()) {
            playlist.getChildren().forEach(childPlaylist -> printChildrenToConsole(childPlaylist));
        }
    }

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

}

uj5u.com熱心網友回復：

有時，最好只用鷹眼從頭開始重新啟動整個架構。在我的情況下，這導致了最好的答案之一......我希望......而且效果很好！

在這種情況下，覆寫的方法getChildren.add(...)是錯誤的方法。

正確的方向是關于事件，在這種情況下addEventHandler：

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableRow;
import javafx.scene.control.TreeTableView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class CustomedTypedTreeTableSample2 extends Application {

    public class TreeTableRowPlaylist extends TreeTableRow<TreeTableRowPlaylist> {

        // Initialized during constructor
        private SimpleStringProperty name;

        public String getName() {
            return name.get();
        }

        public void setName(String name) {
            this.name.set(name);
        }

        public SimpleStringProperty nameProperty() {
            return name;
        }

        public TreeTableRowPlaylist(String name) {
            super();
            this.name = new SimpleStringProperty(name);
        }
    }

    private final class TreeItemPlaylist extends TreeItem<TreeTableRowPlaylist> {
        // private boolean isFirstTimeChildren = true;

        private TreeItemPlaylist(TreeTableRowPlaylist treeTableRowPlaylist) {
            super(treeTableRowPlaylist);

            addEventHandler(TreeItem.childrenModificationEvent(), this::childrenModification);

            // Same code in a 'anonymous' implementation :
//          addEventHandler(TreeItem.childrenModificationEvent(), new EventHandler<TreeModificationEvent<TreeTableRowPlaylist>>() {
//              @Override
//              public void handle(TreeModificationEvent<TreeTableRowPlaylist> event) {
//                  childrenModification(event);
//              }
//          });
        }

        private void childrenModification(TreeModificationEvent<TreeTableRowPlaylist> event) {
            if (event.wasAdded()) {
                for (TreeItem<TreeTableRowPlaylist> item : event.getAddedChildren()) {
                    System.out.println("Node "   item.getValue().getName()   " has been added.");
                }
            }
        }
    }

    private void printChildrenToConsole(TreeItem<TreeTableRowPlaylist> playlist) {
        System.out.println(playlist.getValue().getName());
        if (!playlist.isLeaf()) {
            playlist.getChildren().forEach(childPlaylist -> printChildrenToConsole(childPlaylist));
        }
    }


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

    @Override
    public void start(Stage primaryStage) {
        ///// TreeTableView basics
        // Tree table view
        TreeTableView<TreeTableRowPlaylist> tableView = new TreeTableView<>();
        // Column for the name
        TreeTableColumn<TreeTableRowPlaylist, String> nameColumn = new TreeTableColumn<>("Name");
        nameColumn.setCellValueFactory(param -> param.getValue().getValue().nameProperty());
        // Add column
        tableView.getColumns().addAll(nameColumn);

        ///// Dummy tree building
        tableView.setRoot(new TreeItemPlaylist(new TreeTableRowPlaylist("ROOT")));
        tableView.getRoot().getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf 1")));
        tableView.getRoot().getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf 2")));
        TreeItemPlaylist aTreeBranchA = new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Branch A"));
        aTreeBranchA.getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf A.1")));
        aTreeBranchA.getChildren().add(new TreeItemPlaylist(new TreeTableRowPlaylist("Playlist Leaf A.2")));
        tableView.getRoot().getChildren().add(aTreeBranchA);

        ///// Testing if overriding is working
        // button to get the list of children
        Button display = new Button("Print out children tree to console");
        display.setOnAction(event -> tableView.getRoot().getChildren().forEach(playlist -> printChildrenToConsole(playlist)));

        ///// Setting the GUI
        VBox vbox = new VBox(0, tableView, display);

        Scene scene = new Scene(vbox);

        primaryStage.setScene(scene);
        primaryStage.show();
    }
}