JAVAFX 8 ComboBox and ObservableList - javafx

Question

I need a combobox populated through observablelist which contains specific data retrieved from DB. This is my source.
Model
public ObservableList<Bank> listBank = FXCollections.observableArrayList();
public static class Bank {
private final StringProperty id;
private final StringProperty name;
private Bank(
String id,
String name
) {
this.id = new SimpleStringProperty(id);
this.name = new SimpleStringProperty(name);
}
public StringProperty idProperty() { return id; }
public StringProperty nameProperty() { return name; }
}
View
#FXML
private ComboBox comboBank<Bank>;
public final void getBankDataFields() {
comboBank.setItems(model.listBank);
}
comboBank.setButtonCell(new ListCell<Bank>() {
#Override
protected void updateItem(Bank t, boolean bln) {
super.updateItem(t, bln);
if (t != null) {
setText(t.nameProperty().getValue().toUpperCase());
} else {
setText(null);
}
}
});
comboBank.setCellFactory(new Callback<ListView<Bank>, ListCell<Bank>>() {
#Override
public ListCell<Bank> call(ListView<Bank> p) {
return new ListCell<Bank>() {
#Override
protected void updateItem(Bank t, boolean bln) {
super.updateItem(t, bln);
if(t != null){
setText(t.nomeProperty().getValue().toUpperCase());
} else {
setText(null);
}
}
};
}
});
comboBank.valueProperty().addListener((ObservableValue<? extends Bank> observable, Bank oldValue, Bank newValue) -> {
setIdBank(newValue.idProperty().getValue());
});
ComboBox is populated with NAME field and listener is used to get relative ID and pass it to a query for storing data on DB.
Ok, everything seems to work but i have two questions:
When user need to modify this record, i need to get the ID from DB and select the relative NAME in ComboBox. How can i do that?
comboBank.setValue(????);
Is there a better way to achieve this goal? An ObservableMap may substitute the ObservableList?
Thanks in advance.

Answer 1

There is an easier way to what you are trying to achieve. You should use a StringConverter on the ComboBox to display the names for the Bank instances.
comboBox.setConverter(new StringConverter<Bank>() {
#Override
public String toString(Bank object) {
return object.nameProperty().get();
}
#Override
public Bank fromString(String string) {
// Somehow pass id and return bank instance
// If not important, just return null
return null;
}
});
To get selected value i.e. instance of the selected bank, just use :
comboBox.getValue();
MCVE
import javafx.animation.PauseTransition;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;
import javafx.util.StringConverter;
import java.util.stream.Collectors;
public class Main extends Application {
#Override
public void start(Stage stage) {
ComboBox<Bank> comboBox = new ComboBox<>();
ObservableList<Bank> items = FXCollections.observableArrayList(
new Bank("1", "A"), new Bank("2", "B"),
new Bank("3", "C"), new Bank("4", "D"));
comboBox.setItems(items);
StringConverter<Bank> converter = new StringConverter<Bank>() {
#Override
public String toString(Bank bank) {
return bank.nameProperty().get();
}
#Override
public Bank fromString(String id) {
return items.stream()
.filter(item -> item.idProperty().get().equals(id))
.collect(Collectors.toList()).get(0);
}
};
comboBox.setConverter(converter);
// Print the name of the Bank that is selected
comboBox.getSelectionModel().selectedItemProperty().addListener((o, ol, nw) -> {
System.out.println(comboBox.getValue().nameProperty().get());
});
// Wait for 3 seconds and select the item with id = 2
PauseTransition pauseTransition = new PauseTransition(Duration.seconds(3));
pauseTransition.setOnFinished(event -> comboBox.getSelectionModel().select(converter.fromString("2")));
pauseTransition.play();
VBox root = new VBox(comboBox);
root.setAlignment(Pos.CENTER);
Scene scene = new Scene(root, 200, 200);
stage.setScene(scene);
stage.show();
}
}