Recursive DataModel for JavaFX TreeView/TreeTableView

_README.md

A TreeItem implementation for JavaFX TreeView/TreeTableView that can be used to display recursive data structures.

This file is taken from one of my toy-projects. A more detailed explanation can be found in my blog

RecursiveTreeItem.java

import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.scene.Node;
import javafx.scene.control.TreeItem;
import javafx.util.Callback;

import java.util.List;
import java.util.stream.Collectors;

public class RecursiveTreeItem<T> extends TreeItem<T> {

    private Callback<T, ObservableList<T>> childrenFactory;

    public RecursiveTreeItem(Callback<T, ObservableList<T>> func){
        this(null, func);
    }

    public RecursiveTreeItem(final T value, Callback<T, ObservableList<T>> func){
        this(value, (Node) null, func);
    }

    public RecursiveTreeItem(final T value, Node graphic, Callback<T, ObservableList<T>> func){
        super(value, graphic);

        this.childrenFactory = func;

        if(value != null) {
            addChildrenListener(value);
        }

        valueProperty().addListener((obs, oldValue, newValue)->{
            if(newValue != null){
                addChildrenListener(newValue);
            }
        });
    }

    private void addChildrenListener(T value){
        final ObservableList<T> children = childrenFactory.call(value);

        children.forEach(child ->  RecursiveTreeItem.this.getChildren().add(new RecursiveTreeItem<>(child, getGraphic(), childrenFactory)));

        children.addListener((ListChangeListener<T>) change -> {
            while(change.next()){

                if(change.wasAdded()){
                    change.getAddedSubList().forEach(t-> RecursiveTreeItem.this.getChildren().add(new RecursiveTreeItem<>(t, getGraphic(), childrenFactory)));
                }

                if(change.wasRemoved()){
                    change.getRemoved().forEach(t->{
                        final List<TreeItem<T>> itemsToRemove = RecursiveTreeItem.this.getChildren().stream().filter(treeItem -> treeItem.getValue().equals(t)).collect(Collectors.toList());

                        RecursiveTreeItem.this.getChildren().removeAll(itemsToRemove);
                    });
                }

            }
        });
    }
}

Hello,

i use your class for the data model of a TreeTableView. I've seen you add new objects only at the end. I therefore have a problem because I also have objects, e.g. on the first index. In the observerable list, the object is in the first index, but in the tree view the object is in the last index. Can you extend your class to set an index if i add a new RecusiveTreeItem (line 47)?

Best regards
MS-Tech