combobox cannot be resolved in JavaFX

I want to design one application with a combobox containing items. and while selecting i want to give user autocomplete suggestion. but while doing this combobox is not getting resolved. i have attached the files.

Ademo.fxml

<AnchorPane prefHeight="268.0" prefWidth="290.0" xmlns:fx="http://javafx.com/fxml" fx:controller="v.C_hgj"> <ComboBox layoutX="110.0" layoutY="98.0" fx:id="fruitCombo" prefWidth="90.0" promptText="choose"> <FXCollections fx:factory="observableArrayList"> <String fx:value="Apple" /> <String fx:value="orange" /> <String fx:value="mango" /> <String fx:value="banana" /> <String fx:value="guava" /> <String fx:value="water melon" /> V_hgj.java

package v;

import java.util.logging.Level;
import java.util.logging.Logger;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;

public class V_hgj extends Application{


    public static void main(String[] args) {
        launch(V_hgj.class, (java.lang.String[])null);

    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        try
        {

            //loading .fxml file

            AnchorPane ap=FXMLLoader.load(V_hgj.class.getResource("Ademo.fxml"));
            Scene sc=new Scene(ap);
            primaryStage.setScene(sc);
            primaryStage.setTitle("Product");


            //getting external .css file 
          //  primaryStage.getScene().getStylesheets().add("file:/~/helper/gui.css");
            primaryStage.show();
        }
        catch(Exception ex)
        {
            Logger.getLogger(V_product.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

C_hgj.java

package v;

import java.net.URL; import java.util.ResourceBundle;

import javafx.fxml.FXML; import javafx.fxml.Initializable;

public class C_hgj implements Initializable{

@FXML
private ComboBox fruitCombo;
public static void main(String[] args) {
    // TODO Auto-generated method stub

}

@Override
public void initialize(URL location, ResourceBundle resources) {
    // TODO Auto-generated method stub
    assert fruitCombo!=null : "reset botton not injected";

}

} please help ....