Selecting a TreeItem will display a different scene

I'm creating a stage that displays a TreeTable that has the following TreeItems: Photos, Files and Videos. When a user selects on one of the items I want the scene to change and display either the photos, files or videos.

Here is a snippet of the TreeTable:

I understand how to get the value of the tree item and display.

public void selectedItem(){
    TreeItem<String> item = dataTable.getSelectionModel().getSelectedItem();
    if(item != null){
        System.out.println(item.getValue());
    } else if (item == pngFiles) {
        System.out.println("You've selected PNG Files");
    }        
}

I have also tried to manipulate this code block to have the item variable equal to one of the tree items defined. That didn't work appropriately.

Here is something that may be helpful. You may need tree.getSelectionModel().selectedItemProperty().addListener.

import javafx.application.Application;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.image.ImageView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
 
public class App extends Application {

    private final Node rootIcon = new ImageView(
        //new Image(getClass().getResourceAsStream("folder_16.png"))
    );

    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Tree View Sample");        
        
        TreeItem<String> rootItem = new TreeItem ("Inbox", rootIcon);
        rootItem.setExpanded(true);
        for (int i = 1; i < 6; i++) {
            TreeItem<String> item = new TreeItem ("Message" + i);            
            rootItem.getChildren().add(item);
        }        
        TreeView<String> tree = new TreeView (rootItem);   
        
        BorderPane root = new BorderPane();
        root.setCenter(getViewOne());
        root.setLeft(tree);
        
        tree.getSelectionModel().selectedItemProperty().addListener((obs, oldTreeItem, newTreeItem) -> {
            if(newTreeItem != null)
            {
                if(newTreeItem == rootItem.getChildren().get(0))
                {
                    root.setCenter(getViewOne());
                }
                if(newTreeItem == rootItem.getChildren().get(1))
                {
                    root.setCenter(getViewTwo());
                }
                else
                {
                    System.out.println("Write code for other cases!");
                }
            }
        });
        
        primaryStage.setScene(new Scene(root, 500, 500));
        primaryStage.show();
    }
    
    
    public HBox getViewOne()
    {
        return new HBox(new Label("View One"));
    }
    
    public StackPane getViewTwo()
    {
        return new StackPane(new Label("View Two"));
    }
}

Edit: You can also do something like the following.

tree.getSelectionModel().selectedItemProperty().addListener((obs, oldTreeItem, newTreeItem) -> {
    if(newTreeItem != null)
    {
        if(newTreeItem.getValue().equals("Message1"))
        {
            root.setCenter(getViewOne());
        }
        if(newTreeItem.getValue().equals("Message2"))
        {
            root.setCenter(getViewTwo());
        }
        else
        {
            System.out.println("Write code for other cases!");
        }
    }
});

Altered code from https://docs.oracle.com/javafx/2/ui_controls/tree-view.htm.