javafx checkBoxTableCell callback - javafx

Question

I would like to ask what is the most elegant way to capture value change of CheckBoxTableCell in my TableView.
My goal is to save new value in DB which my example shows:
printedColumn.setCellValueFactory(f -> f.getValue().getPrintedProperty());
printedColumn.setCellFactory(CheckBoxTableCell.forTableColumn(new Callback<Integer, ObservableValue<Boolean>>() {
#Override
public ObservableValue<Boolean> call(Integer param) {
ProductFx productFx = addProductModel.getProductFxObservableList().get(param);
updateInDatabase(productFx);
return productFx.getPrintedProperty();
}
}));
This works fine, but I don't feel like it's the best way to achieve that. For other columns I follow this way:
#FXML
public void onEditPrice(TableColumn.CellEditEvent<ProductFx, Number> e) {
ProductFx productFx = e.getRowValue();
productFx.setPrice(e.getNewValue().doubleValue());
updateInDatabase(productFx);
}
fxml:
<TableColumn fx:id="priceColumn" onEditCommit="#onEditPrice" prefWidth="75.0" text="%addProductTable.price" />
Is it possible to do it in similar way with #FXML annotated method and fxml configuration? Maybe some other ideas?

Answer 1

I really find it hard to get the idea behind your question. I publish the code how I think it should be done. If it does not meet your requirements please elaborate on what you are exactly trying to achive.
import javafx.application.Application;
import javafx.beans.property.LongProperty;
import javafx.beans.property.SimpleLongProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.stage.Stage;
public class TableViewApp extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage stage) throws Exception {
ObservableList<Product> products = FXCollections.observableArrayList(product -> new ObservableValue[] {product.nameProperty()});
products.add(new Product(1l, "Machine1"));
products.add(new Product(2l, "Machine2"));
products.addListener((ListChangeListener<Product>) change -> {
while (change.next()) {
if (change.wasUpdated()) {
for (int i = change.getFrom(); i < change.getTo(); i++) {
updateInDb(change.getList().get(i));
}
}
}
});
TableView<Product> tableView = new TableView<>(products);
tableView.setEditable(true);
TableColumn<Product, Long> idColumn = new TableColumn<>("Id");
idColumn.setCellValueFactory(cellData -> cellData.getValue().idProperty().asObject());
TableColumn<Product, String> nameColumn = new TableColumn<>("Name");
nameColumn.setCellValueFactory(cellData -> cellData.getValue().nameProperty());
nameColumn.setCellFactory(TextFieldTableCell.forTableColumn());
nameColumn.setEditable(true);
tableView.getColumns().add(idColumn);
tableView.getColumns().add(nameColumn);
stage.setScene(new Scene(tableView));
stage.show();
}
private void updateInDb(Product product) {
System.out.println("Update " + product + " in db");
}
}
class Product {
private LongProperty id = new SimpleLongProperty();
private StringProperty name = new SimpleStringProperty();
public Product(long id, String name) {
this.id.set(id);
this.name.set(name);
}
public LongProperty idProperty() {
return id;
}
public long getId() {
return id.get();
}
public StringProperty nameProperty() {
return name;
}
public String getName() {
return name.get();
}
#Override
public String toString() {
return "Product[id=" + getId() + ", name=" + getName() + "]";
}
}

Answer 2

I do not understand in detail how you got your code working. I guess it is not working as intended by the design of the API. I can definitely answer if it is possible to do it with a simple FXML attribute of CheckBoxTableCell: No.
In case of CheckBoxTableCell
... it is not necessary that the cell enter its editing state (...). A side-effect of this is that the usual editing callbacks (such as on edit commit) will not be called. If you want to be notified of changes,
it is recommended to directly observe the boolean properties that are
manipulated by the CheckBox.
as stated by the javadoc.
If the class of printedProperty implements ObservableValue<Boolean>(as stated by your code) you should follow the cited doc and add a ChangeListener to it like
printedColumn.setCellValueFactory(f -> f.getValue().getPrintedProperty());
printedColumn.setCellFactory(CheckBoxTableCell.forTableColumn(new Callback<Integer, ObservableValue<Boolean>>() {
#Override
public ObservableValue<Boolean> call(Integer param) {
ProductFx productFx = addProductModel.getProductFxObservableList().get(param);
return productFx.getPrintedProperty();
}
}));
ObservableList<ProductFx> obs = addProductModel.getProductFxObservableList();
obs.addListener(new ListChangeListener<ProductFx>(){
#Override
public void onChanged(Change<? extends ProductFx> c) {
if(c.wasAdded()) {
for (ProductFx s:c.getAddedSubList()) {
s.getPrintedProperty().addListener(new ChangeListener<Boolean>() {
ProductFx localProductFx=s;
#Override
public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
updateInDatabase(localProductFx);
}
});
}
}
}
});
But this is not elegant at all.
To your approach to solve the problem:
The Callback<Integer, ObservableValue<Boolean>>() you used is called each time when the displayed cell is updated. This happens especially when you are scrolling through a huge list, because TableView only keeps as many Cell instances as necessary to fill its view-port (doc). They are simply updated during scrolling and your code updates the database each time this happens, so you might run into performance problems for large datasets or slow databases.
PS: As far as I understand your code you do not follow the usual naming conventions for properties. This might lead to problems using reflecting classes like PropertyValueFactory.