JavaFX ComboBox setButtonCell - combobox

Question

i need help about settings the combobox buttonCell.
I use a combobox that show data from an observable list that contains data from a table with two columns, "Step" and "NextStep" (NextStep contains one item inserted in column Step); what i need to do is to show the combobox listcell with the list of "Step" and the buttoncell with the relative "NextStep". Now, i can see the listcell correctly but my buttoncell is always empty.
The code:
// SET THE VALUE STEP TO THE LISTCELL
comboStatoSuccessivo.setCellFactory(new Callback<ListView<StatoEsiti>, ListCell<StatoEsiti>>() {
#Override public ListCell<StatoEsiti> call(ListView<StatoEsiti> p) {
return new ListCell<StatoEsiti>() {
#Override
protected void updateItem(StatoEsiti t, boolean bln) {
super.updateItem(t, bln);
if(t != null){
setText(t.statoProperty().getValue());
System.out.println("SET PROPERTY " + t.statoProperty().getValue());
} else {
setText(null);
}
}
};
}
});
// SET THE VALUE NEXTSTEP TO THE BUTTONCELL
comboStatoSuccessivo.setButtonCell(new ListCell<StatoEsiti>() {
#Override
protected void updateItem(StatoEsiti t, boolean bln) {
super.updateItem(t, bln);
if (t != null) { <<<<<<<<<<<<<<-------------ALWAYS NULL----WHY??????
setText(t.statoSuccessivoProperty().getValue());
System.out.println("SET PROPERTY BUTTONCELL " + t.statoSuccessivoProperty().getValue());
} else {
setText(null);
System.out.println("SET PROPERTY BUTTONCELL NULL");
}
}
});
Thanks in advance.

Answer 1

I have looked into your use case with the following demo SSCCE code.
It is working as expected, like as when the item is selected from the combobox's dropmenu the buttoncell is updated with related "nextStep":
public class ComboDemo extends Application {
#Override
public void start(Stage primaryStage) {
List<Person> list = new ArrayList<Person>();
list.add(new Person("step 1212", 12));
list.add(new Person("step 4545", 45));
list.add(new Person("step 5656", 56));
list.add(new Person("step 9090", 90));
ComboBox<Person> comboBox = new ComboBox<>(FXCollections.observableList(list));
comboBox.setCellFactory(new Callback<ListView<Person>, ListCell<Person>>() {
#Override
public ListCell<Person> call(ListView<Person> p) {
return new ListCell<Person>() {
#Override
protected void updateItem(Person t, boolean bln) {
super.updateItem(t, bln);
if (t != null) {
setText(t.getStepProperty().getValue());
System.out.println("SET PROPERTY " + t.getStepProperty().getValue());
} else {
setText(null);
}
}
};
}
});
// SET THE VALUE NEXTSTEP TO THE BUTTONCELL
comboBox.setButtonCell(new ListCell<Person>() {
#Override
protected void updateItem(Person t, boolean bln) {
super.updateItem(t, bln);
if (t != null) {
setText(t.getNextStepProperty().getValue().toString());
System.out.println("SET PROPERTY BUTTONCELL " + t.getNextStepProperty().getValue());
} else {
setText(null);
System.out.println("SET PROPERTY BUTTONCELL NULL");
}
}
});
StackPane root = new StackPane();
root.getChildren().add(comboBox);
Scene scene = new Scene(root, 300, 250);
primaryStage.setScene(scene);
primaryStage.show();
}
public static class Person {
private StringProperty stepProperty = new SimpleStringProperty();
private IntegerProperty nextStepProperty = new SimpleIntegerProperty();
public Person(String step, Integer nextStep) {
this.stepProperty.setValue(step);
this.nextStepProperty.setValue(nextStep);
}
public StringProperty getStepProperty() {
return stepProperty;
}
public void setStepProperty(StringProperty stepProperty) {
this.stepProperty = stepProperty;
}
public IntegerProperty getNextStepProperty() {
return nextStepProperty;
}
public void setNextStepProperty(IntegerProperty nextStepProperty) {
this.nextStepProperty = nextStepProperty;
}
}
public static void main(String[] args) {
launch(args);
}
}
Compare it with yours.