ContextMenu in JavaFX keeps getting duplicates of the same MenuItem - javafx

Question

I use this class to give a TreeItem a textfield for editing (not relevant to the problem) and to set a ContextMenu on the TreeItem:
package domain;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.MenuItem;
import javafx.scene.control.TextField;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
public final class TextFieldTreeCellImpl extends TreeCell<MyNode> {
private TextField textField;
private ContextMenu cm = new ContextMenu();
String oldItem = "";
private Connection connection;
String url = "jdbc:sqlserver://localhost:1433;databaseName=HOGENT1415_11";
String user = "sa";
String password = "root";
Statement statement;
public TextFieldTreeCellImpl() throws SQLException {
connection = DriverManager.getConnection(url, user, password);
statement = connection.createStatement();
}
#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().value);
setGraphic(getTreeItem().getGraphic());
}
#Override
public void updateItem(MyNode 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());
MenuItem cmItem1 = new MenuItem("Add continent");
cmItem1.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
System.out.println("Geklikt!");
}
});
cm.getItems().add(cmItem1);
setContextMenu(cm);
}
}
}
private void createTextField() {
textField = new TextField(getString());
textField.setOnKeyReleased(new EventHandler<KeyEvent>() {
#Override
public void handle(KeyEvent t) {
if (t.getCode() == KeyCode.ENTER) {
String sql = "UPDATE Continents SET Name='" + textField.getText() + "' WHERE ContinentID=" + getItemId();
if (getItem().isCountry()) {
sql = "UPDATE Countries SET Name='" + textField.getText() + "' WHERE CountryID=" + getItemId();
}
if (getItem().isClimateChart()) {
sql = "UPDATE ClimateCharts SET Location='" + textField.getText() + "' WHERE ClimateChartID=" + getItemId();
}
try {
ResultSet result = statement.executeQuery(sql);
} catch (SQLException ex) {
Logger.getLogger(TextFieldTreeCellImpl.class.getName()).log(Level.SEVERE, null, ex);
}
commitEdit(new MyNode(textField.getText(), getType(), getItemId()));
} else if (t.getCode() == KeyCode.ESCAPE) {
cancelEdit();
}
}
});
}
private String getString() {
return getItem() == null ? "" : getItem().toString();
}
private String getType() {
return getItem() == null ? "" : getItem().type;
}
private int getItemId() {
return getItem() == null ? null : getItem().id;
}
}
I instance this class in my Controller class using the following code:
selectionTreeView.setEditable(true);
selectionTreeView.setCellFactory(new Callback<TreeView<MyNode>, TreeCell<MyNode>>() {
#Override
public TreeCell<MyNode> call(TreeView<MyNode> p) {
try {
return new TextFieldTreeCellImpl();
} catch (SQLException ex) {
Logger.getLogger(MainPanel.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
});
However when I run the program and I right click on the items everything works fine, but if I keep clicking some more on other items there keep on getting items in the contextmenu.
To narrow it down, this happens everytime I double click on an item.
Check the screenshots:
I know that this is because ipdateItem keeps on getting called, but how can I prevent this?

Answer 1

Every time updateItem(...) is called, you add the menu item again (and you never remove it). So each time the cell is reused, it gets another copy of the menu item.
The most efficient approach is to create the menu item in the constructor and pass it to the context menu there. Note that the event handler can access the current item easily:
public TextFieldTreeCellImpl() throws SQLException {
connection = DriverManager.getConnection(url, user, password);
statement = connection.createStatement();
MenuItem cmItem1 = new MenuItem("Add continent");
cmItem1.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
MyNode item = getItem();
// ...
System.out.println("Geklikt!");
}
});
cm.getItems().add(cmItem1);
}
You probably also want to remove the context menu for empty cells:
#Override
public void updateItem(MyNode item, boolean empty) {
super.updateItem(item, empty);
if (empty) {
setText(null);
setGraphic(null);
setContextMenu(null);
} else {
if (isEditing()) {
if (textField != null) {
textField.setText(getString());
}
setText(null);
setGraphic(textField);
} else {
setText(getString());
setGraphic(getTreeItem().getGraphic());
setContextMenu(cm);
}
}
}
You can also configure the menu items further in the updateItem(...) method if you need, by declaring them as fields, e.g.
public final class TextFieldTreeCellImpl extends TreeCell<MyNode> {
private TextField textField;
private ContextMenu cm = new ContextMenu();
private MenuItem cmItem1 ;
// ...
#Override
public void updateItem(MyNode item, boolean empty) {
super.updateItem(item, empty);
// ...
cmItem1.setText(...);
}
}
Finally, if you really need to completely restructure the context menu when the item changes, then you can do
#Override
public void updateItem(MyNode item, boolean empty) {
super.updateItem(item, empty);
// ...
cm.getItems().clear();
// Now create all menu items from scratch and add to the context menu
}