Java CategoryAxis .toRealValue (double value)

public java.lang.String toRealValue(double value)

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
 // w  w w.j  a  v  a  2  s . c  o  m
public class Main extends Application {

    @Override
    public void start(final Stage stage) {
        stage.setWidth(500);
        stage.setHeight(500);
        Scene scene = new Scene(new Group());

        VBox root = new VBox();     
        CategoryAxis lineXAxis = new CategoryAxis(getData());
        
        System.out.println(lineXAxis.toRealValue(1.2));
        
        root.getChildren().addAll(lineXAxis);
        scene.setRoot(root);

        stage.setScene(scene);
        stage.show();
    }
    private ObservableList<String> getData() {
      ObservableList<String> answer = FXCollections.observableArrayList();
      answer.addAll("Sales","Products");
      return answer;
    }
    public static void main(String[] args) {
        launch(args);
    }
}