The sample referenced below can be found at http://docs.oracle.com/javase/8/javafx/user-interface-tutorial/samples.htm.

The exact same steps do not always reproduce this bug; however, it is fairly easy to reproduce, after a few attempts. The steps below are not always necessary to get this bug to occur, but they most consistently reproduce the issue for me. To try to repeat it:

 

1) Run TreeViewSample.java from Eclipse as an application.

2) Add an employee to "IT Support." Rename the employee. Do this again.

3) Double-click on those employees again. Continue double-clicking on other employees' names repetitively, without hitting Esc to exit out of the other text fields. (I am not sure if hitting Esc is important or not.) Eventually, an incorrect name will be displayed in the text field -- it will display a name from somewhere else in the list. The incorrect name that it displays will be from a textfield that has already been opened.

 

The workaround for this is to modify the following function as below:

 

            @Override
            public void startEdit()
            {
                super.startEdit();
      
                if (textField == null)
                {
                    createTextField();
                }
                textField.setText(getString());
                setText(null);
                setGraphic(textField);
                textField.selectAll();
            }

 
The addition of textField.setText(getString()); is the only change. This ensures that the textField displays the correct value.

 

After adding debug statements in the sample code, I noticed that the function createTextField() is not always being called when I think it should be, i.e. when an employee that has not been edited before is selected for editing. This leads me to suspect that somehow, as discussed by jsmith on https://community.oracle.com/thread/3620425, "the cell gets reused to display data for a new item and the textfield associated with the cell is not always correctly updated to reflect the value of the new item."

The entire contents of the original TreeViewSample.java are:

/*
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 *
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 *
 * - Redistributions of source code must retain the above copyright
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package treeviewsample;

import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

import javafx.beans.property.SimpleStringProperty;
import javafx.event.ActionEvent;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.VBox;

public class TreeViewSample extends Application {

    private final Node rootIcon =
        new ImageView(new Image(getClass().getResourceAsStream("root.png")));
    private final Image depIcon =
        new Image(getClass().getResourceAsStream("department.png"));
    List<Employee> employees = Arrays.<Employee>asList(
            new Employee("Jacob Smith", "Accounts Department"),
            new Employee("Isabella Johnson", "Accounts Department"),
            new Employee("Ethan Williams", "Sales Department"),
            new Employee("Emma Jones", "Sales Department"),
            new Employee("Michael Brown", "Sales Department"),
            new Employee("Anna Black", "Sales Department"),
            new Employee("Rodger York", "Sales Department"),
            new Employee("Susan Collins", "Sales Department"),
            new Employee("Mike Graham", "IT Support"),
            new Employee("Judy Mayer", "IT Support"),
            new Employee("Gregory Smith", "IT Support"));
    TreeItem<String> rootNode =
        new TreeItem<>("MyCompany Human Resources", rootIcon);

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

    @Override
    public void start(Stage stage) {
        rootNode.setExpanded(true);
        for (Employee employee : employees) {
            TreeItem<String> empLeaf = new TreeItem<>(employee.getName());
            boolean found = false;
            for (TreeItem<String> depNode : rootNode.getChildren()) {
                if (depNode.getValue().contentEquals(employee.getDepartment())){
                    depNode.getChildren().add(empLeaf);
                    found = true;
                    break;
                }
            }
            if (!found) {
                TreeItem depNode = new TreeItem(employee.getDepartment(),
                    new ImageView(depIcon)
                );
                rootNode.getChildren().add(depNode);
                depNode.getChildren().add(empLeaf);
            }
        }

        stage.setTitle("Tree View Sample");
        VBox box = new VBox();
        final Scene scene = new Scene(box, 400, 300);
        scene.setFill(Color.LIGHTGRAY);

        TreeView<String> treeView = new TreeView<>(rootNode);
        treeView.setShowRoot(true);
        treeView.setEditable(true);
        treeView.setCellFactory((TreeView<String> p) ->
            new TextFieldTreeCellImpl());

        box.getChildren().add(treeView);
        stage.setScene(scene);
        stage.show();
    }

    private final class TextFieldTreeCellImpl extends TreeCell<String> {

        private TextField textField;
        private final ContextMenu addMenu = new ContextMenu();

        public TextFieldTreeCellImpl() {
            MenuItem addMenuItem = new MenuItem("Add Employee");
            addMenu.getItems().add(addMenuItem);
            addMenuItem.setOnAction((ActionEvent t) -> {
                TreeItem newEmployee =
                        new TreeItem<>("New Employee");
                getTreeItem().getChildren().add(newEmployee);
            });
        }

        @Override
        public void startEdit() {
            super.startEdit();

            if (textField == null) {
                createTextField();
            }
            setText(null);
            setGraphic(textField);
            textField.selectAll();
        }

        @Override
        public void cancelEdit() {
            super.cancelEdit();

            setText((String) getItem());
            setGraphic(getTreeItem().getGraphic());
        }

        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);

            if (empty) {
                setText(null);
                setGraphic(null);
            } else {
                if (isEditing()) {
                    if (textField != null) {
                        textField.setText(getString());
                    }
                    setText(null);
                    setGraphic(textField);
                } else {
                    setText(getString());
                    setGraphic(getTreeItem().getGraphic());
                    if (!getTreeItem().isLeaf()&&getTreeItem().getParent()!= null){
                        setContextMenu(addMenu);
                    }
                }
            }
        }
        
        private void createTextField() {
            textField = new TextField(getString());
            textField.setOnKeyReleased((KeyEvent t) -> {
                if (t.getCode() == KeyCode.ENTER) {
                    commitEdit(textField.getText());
                } else if (t.getCode() == KeyCode.ESCAPE) {
                    cancelEdit();
                }
            });
            
        }

        private String getString() {
            return getItem() == null ? "" : getItem().toString();
        }
    }

    public static class Employee {

        private final SimpleStringProperty name;
        private final SimpleStringProperty department;

        private Employee(String name, String department) {
            this.name = new SimpleStringProperty(name);
            this.department = new SimpleStringProperty(department);
        }

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

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

        public String getDepartment() {
            return department.get();
        }

        public void setDepartment(String fName) {
            department.set(fName);
        }
    }
}