请原谅我英语不好。我已经开始了一个项目，我们的导师要求我用javafx构建一个应用程序。当我想在gridpane上添加按钮时，我使用了scenebuilder for fxml部分，它不起作用。与数据库的连接正常。在应用程序的第一部分，用户在登录之后进入userwindow，但按钮没有显示。
main.java文件：

package sample;

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

public class Main extends Application {
    Stage window;
    Controller c;
    ControllerB cB;

    @Override
    public void start(Stage primaryStage) throws Exception{
        window = primaryStage;

        FXMLLoader f = new FXMLLoader();
        FXMLLoader f2 = new FXMLLoader();
        f.setLocation(Main.class.getResource("sample.fxml"));
        f2.setLocation(Main.class.getResource("UserWindow.fxml"));

        Parent root = f.load();
        Parent root2 = f2.load();
        Scene s = new Scene(root, 500, 340);

        //Controllers
        c = f.getController();
        c.setMain(this);
        c.setScene2(new Scene(root2, 900, 500));

        cB = f2.getController();
        cB.setMain(this);
        cB.setScene(s);

        window.setTitle("Remote Works");
        window.setScene(s);
        window.show();
    }

    public static void main(String[] args) {
        launch(args);
    }

    public void setUserData(Object o){
        window.setUserData(o);
    }

    public void setScene(Scene scene){
        window.setScene(scene);
        window.show();
    }

    public void setScene2(Scene scene){
        window.setScene(scene);
        window.show();
    }
}

controllerb.java文件：

package sample;

import javafx.collections.*;
import javafx.event.ActionEvent;
import javafx.fxml.*;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.layout.GridPane;
import java.io.IOException;
import java.net.URL;
import java.sql.*;
import java.util.*;

public class ControllerB implements Initializable {

    @FXML
    private GridPane Box;

    @FXML
    private Label nameUser;

    @FXML
    private Label matriculeUser;

    @FXML
    private Label fonctionUser;

    @FXML
    private Button deconnect;

    private Scene scene1;
    private Main main;
    ObservableList<String> ecoles;

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle){
        try{
            schoolretrieve();
            int size = ecoles.size();
            Node[] n = new Node[size];
            for (int i = 0; i < n.length; i++) {
                FXMLLoader loader = new FXMLLoader(getClass().getResource("Bloc.fxml"));
                ControllerItem controller = new ControllerItem();
                loader.setController(controller);
                n[i] = loader.load();
                controller.setButtonInst(ecoles.get(i));//Until this part all works
                Box.getChildren().add(n[i]);//But it doesn't add buttons to GridPane
            }
        } catch (IOException | NullPointerException | SQLException e) {
            //System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }

}

controlleritem.java文件：

package sample;

import javafx.fxml.FXML;

import javafx.scene.control.Button;

public class ControllerItem{

    @FXML
    private Button buttonInst;

    public Button getButtonInst() {
        return buttonInst;
    }

    public void setButtonInst(String s) {
        buttonInst.setText(s);
    }

}

bloc.fxml：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.*?>

<Button fx:id="buttonInst" mnemonicParsing="false" prefHeight="132.0" prefWidth="201.0" stylesheets="@../styles.css" xmlns="http://javafx.com/javafx/10.0.2-internal" xmlns:fx="http://javafx.com/fxml/1" />

用户窗口.fxml:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.shape.*?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="497.0" prefWidth="710.0" styleClass="pane" stylesheets="@../styles.css" xmlns="http://javafx.com/javafx/10.0.2-internal" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.ControllerB">
   <left>
      <Pane prefHeight="497.0" prefWidth="156.0" BorderPane.alignment="CENTER">
         <children>
            <ImageView fitHeight="150.0" fitWidth="151.0" layoutX="11.0" pickOnBounds="true" preserveRatio="true" />
            <Circle fill="#e1ebf5" layoutX="78.0" layoutY="88.0" opacity="0.18" radius="74.0" stroke="BLACK" strokeType="INSIDE" />
            <Label fx:id="nameUser" layoutX="10.0" layoutY="196.0" prefHeight="50.0" prefWidth="136.0" text="Nom Utilisateur :" />
            <Label fx:id="fonctionUser" layoutX="11.0" layoutY="259.0" prefHeight="37.0" prefWidth="136.0" text="Statut : " />
            <Label fx:id="matriculeUser" layoutX="10.0" layoutY="306.0" prefHeight="37.0" prefWidth="136.0" text="Identifiant : " />
            <Button fx:id="deconnect" layoutX="20.0" layoutY="364.0" mnemonicParsing="false" onAction="#onAction" prefHeight="27.0" prefWidth="117.0" text="deconnexion" />
         </children>
      </Pane>
   </left>
   <center>
       <Pane opacity="0.0" prefHeight="200.0" prefWidth="200.0" style="-fx-background-color: #f7cc3d;"
             BorderPane.alignment="CENTER">
           <GridPane fx:id="Box" alignment="TOP_CENTER" hgap="3.0" layoutX="70.0" layoutY="96.0"
                     nodeOrientation="LEFT_TO_RIGHT" opacity="0.95" prefHeight="305.0" prefWidth="415.0"
                     styleClass="gridpane" stylesheets="@../ss.css" vgap="3.0"/>

       </Pane>
   </center>
</BorderPane>