Add change listener to ComboBox valueProperty

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.Callback;

public class Main extends Application {
public static void main(String[] args) {
launch(args);
}

@Override
public void start(Stage stage) {
stage.setTitle("ComboBoxSample");
Scene scene = new Scene(new Group(), 450, 250);

ComboBox emailComboBox = new ComboBox();
emailComboBox.getItems().addAll("A","B","C","D","E");
emailComboBox.setPromptText("Email address");
emailComboBox.setEditable(true);
emailComboBox.valueProperty().addListener(new ChangeListener<String>() {
@Override public void changed(ObservableValue ov, String t, String t1) {
System.out.println(ov);
System.out.println(t);
System.out.println(t1);
}
});

GridPane grid = new GridPane();
grid.setVgap(4);
grid.setHgap(10);
grid.setPadding(new Insets(5, 5, 5, 5));
grid.add(new Label("To: "), 0, 0);
grid.add(emailComboBox, 1, 0);

Group root = (Group) scene.getRoot();
root.getChildren().add(grid);
stage.setScene(scene);
stage.show();

}
}