JavaFX TableView items do not change after changes to the table in the UI - callback

Question

I have a TableView which I populate with MappingItem objects. The goal is to create a mapping between an Excel source fields to database fields.
In the TableView I have two columns. One is of <MappingItem, String> and represents an Excel header. The other is of <MappingItem, GoldplusField> and represents a database field. The second column's cells are ComboBoxTableCell which has a list of fields from my DB.
The problem is that after I change the selection in the second column combobox, the MappingItem does not get updated by my selection. I tried to get the selected Cell and extract the item but I always get Null references.
This is the UI:
This is a sample code:
package tableviewexample;
import javafx.application.Application;
import javafx.beans.property.ReadOnlyObjectWrapper;
import javafx.beans.value.ObservableValue;
import javafx.collections.*;
import javafx.event.*;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.control.cell.ComboBoxTableCell;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.util.Callback;
import javafx.util.StringConverter;
public class TableViewExample extends Application {
#Override
public void start(Stage primaryStage) {
TableView<MappingItem> table = new TableView<>();
// FIRST COLUMN
TableColumn<MappingItem, String> colA = new TableColumn<>("Excel Column");
colA.setCellValueFactory(new Callback<TableColumn.CellDataFeatures<MappingItem, String>, ObservableValue<String>> () {
#Override
public ObservableValue<String> call(TableColumn.CellDataFeatures<MappingItem, String> param) {
return new ReadOnlyObjectWrapper(param.getValue().getExcelColumnName());
}
});
//SECOND COLUMN
TableColumn<MappingItem, GoldplusField> colB = new TableColumn<>("Database Field Column");
colB.setCellValueFactory(new Callback<TableColumn.CellDataFeatures<MappingItem, GoldplusField>, ObservableValue<GoldplusField>> () {
#Override
public ObservableValue<GoldplusField> call(TableColumn.CellDataFeatures<MappingItem, GoldplusField> param) {
return new ReadOnlyObjectWrapper(param.getValue().getGpField());
}
});
GoldplusField gp1 = new GoldplusField("T1", "fName", "First Name");
GoldplusField gp2 = new GoldplusField("T1", "phn", "Phone");
ObservableList<GoldplusField> fieldsList = FXCollections.observableArrayList(gp1, gp2);
colB.setCellFactory(ComboBoxTableCell.forTableColumn(new FieldToStringConvertor(), fieldsList));
colB.setOnEditCommit(new EventHandler<TableColumn.CellEditEvent<MappingItem, GoldplusField>>() {
public void handle(TableColumn.CellEditEvent<MappingItem, GoldplusField> e) {
GoldplusField gpf = colB.getCellData(table.getFocusModel().getFocusedItem());
System.out.println(gpf.getGpName());
MappingItem item = table.getSelectionModel().getSelectedItem();
System.out.println(item.getGpField().getGpName());
}
});
table.setEditable(true);
table.getColumns().addAll(colA, colB);
MappingItem mi1 = new MappingItem("name");
MappingItem mi2 = new MappingItem("phone");
ObservableList<MappingItem> miList = FXCollections.observableArrayList(mi1, mi2);
table.setItems(miList);
StackPane root = new StackPane();
root.getChildren().add(table);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
class FieldToStringConvertor extends StringConverter<GoldplusField> {
#Override
public String toString(GoldplusField object) {
if (object != null)
return object.getGpName();
else
return "";
}
#Override
public GoldplusField fromString(String string) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
}
class MappingItem {
private String excelColumnName;
private GoldplusField gpField;
public String getExcelColumnName() { return excelColumnName; }
public void setExcelColumnName(String excelColumnName) { this.excelColumnName = excelColumnName; }
public GoldplusField getGpField() { return gpField; }
public void setGpField(GoldplusField gpField) { this.gpField = gpField; }
public MappingItem(String columnName) {
this.excelColumnName= columnName;
}
public MappingItem(GoldplusField gpField) {
this.gpField = gpField;
}
public MappingItem(String columnName, GoldplusField gpField) {
this.excelColumnName = columnName;
this.gpField = gpField;
}
}
class GoldplusField {
private String table;
private String dbName;
private String gpName;
public String getDbName() { return dbName; }
public String getGpName() { return gpName; }
public String getTable() { return table; }
public void setDbName(String dbName) { this.dbName = dbName; }
public void setGpName(String gpName) { this.gpName = gpName; }
public void setTable(String table) { this.table = table; }
public GoldplusField(String table, String dbName, String gpName) {
this.dbName = dbName;
this.gpName = gpName;
this.table = table;
}
}
}

Answer 1

OK. As have been mentioned, the problem was, probably, that the properties were not "writable".
I ended up changing my objects properties to JavaFX Properties. Then I set up a PropertyValueFactory for each of them and passed it to the column's CellValueFactory.
Thank you.
private void populateSourceColumnsColumn() {
ArrayList<MappingItem> items = new ArrayList<> ();
ArrayList<String> headers = SheetHelper.getTableHeadersAsString(sheet, true);
for (String header : headers) {
items.add(new MappingItem(header) );
}
ObservableList<MappingItem> itemsList = FXCollections.observableArrayList(items);
mappingTable.setItems(itemsList);
// First Column
PropertyValueFactory<MappingItem, String> fNameCellValueFactory = new PropertyValueFactory<>("excelColumnName");
inputColumnsColumn.setCellValueFactory(fNameCellValueFactory);
// Second Column
PropertyValueFactory<MappingItem, GoldplusField> gpFieldCellValueFactory = new PropertyValueFactory<>("gpField");
goldplusFieldsColumn.setCellValueFactory(gpFieldCellValueFactory);
GoldplusDatabase gpDb = new GoldplusDatabase(DatasourceContext.INSTANCE.getDataSource());
ObservableList<GoldplusField> fieldsList = FXCollections.observableArrayList(gpDb.getContactFields());
goldplusFieldsColumn.setCellFactory(ComboBoxTableCell.forTableColumn(new FieldToStringConvertor(), fieldsList));
}
public class MappingItem {
private StringProperty excelColumnName = new SimpleStringProperty(this, "excelColumnName");
private ObjectProperty<GoldplusField> gpField = new SimpleObjectProperty<GoldplusField>(this, "gpField");
public String getExcelColumnName() {
return excelColumnName.get();
}
public void setExcelColumnName(String excelColumnName) {
this.excelColumnName.set(excelColumnName);
}
public StringProperty excelColumnNameProperty() {
return excelColumnName;
}
public GoldplusField getGpField() {
return gpField.get();
}
public void setGpField(GoldplusField gpField) {
this.gpField.set(gpField);
}
public ObjectProperty gpFieldProperty() {
return this.gpField;
}
public MappingItem() {
super();
}
public MappingItem(String columnName) {
this.excelColumnName.set(columnName);
}
public MappingItem(GoldplusField gpField) {
this.gpField.set(gpField);
}
public MappingItem(String columnName, GoldplusField gpField) {
this.excelColumnName.set(columnName);
this.gpField.set(gpField);
}
}
public class GoldplusField {
private StringProperty table = new SimpleStringProperty(this, "table");
private StringProperty dbName = new SimpleStringProperty(this, "dbName");
private StringProperty gpName = new SimpleStringProperty(this, "gpName");
public String getDbName() {
return dbName.get();
}
public String getGpName() {
return gpName.get();
}
public String getTable() {
return table.get();
}
public void setDbName(String dbName) {
this.dbName.set(dbName);
}
public void setGpName(String gpName) {
this.gpName.set(gpName);
}
public void setTable(String table) {
this.table.set(table);
}
public StringProperty tableProperty() {
return this.table;
}
public StringProperty gpNameProperty() {
return this.gpName;
}
public StringProperty dbNameProperty() {
return this.dbName;
}
public GoldplusField(String table, String dbName, String gpName) {
this.dbName.set(dbName);
this.gpName.set(gpName);
this.table.set(table);
}
}