JAVAFX: Switching Between Panes in BorderPane

I have a desktop app that contains:

Main Class: that load the first fxml file -> SideBar.fxml

SideBar.fxml: contains BorderPane -> at the left of it, i create 2 buttons:

         - the fist button: load  sample fxml file
- the second button: load secondFxml file

sample.fxml: contains a tableView and a Button
secondFxml.fxml: contains a label

Controller: a class that control sample.fxml -> load random double values to a tableView

the issue is :

when i press the button (fill Table) in Pane 1 : it load the data to the tableView, untill now everything is going well

when i switch to the second pane and i return to the first pane the center border pane is reloaded again so the data of the tableView disappeared

what i want is when i return to the first pane the the table view stay as it was first
i try to hide the borderpane center but it doesn't work for me

i screenShot the issue:

Main:

public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("SideBar.fxml"));
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, 700, 500));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

SideBarController:

public class SideBarController implements Initializable {
@FXML BorderPane borderPane;
public void openPane1(ActionEvent event) throws Exception {
loadScene("Sample.fxml");
}
public void openPane2(ActionEvent event) throws Exception {
loadScene("secondFxml.fxml");
}
private void loadScene(String sc) throws IOException {
Parent root = FXMLLoader.load(getClass().getResource(sc));
borderPane.setCenter(root);
}
@Override
public void initialize(URL location, ResourceBundle resources) { }
}

Controller:

public class Controller implements Initializable {
double[][] data = new double[5][5];
Random random = new Random();
ObservableList<double[]> observableLists = FXCollections.observableArrayList();
@FXML
TableView<double []> tableView = new TableView<>(observableLists);
@FXML
public void fillTable(ActionEvent event) throws IOException {
//Random Values
for (int i = 0; i <data.length ; i++) {
for (int j = 0; j <data[0].length ; j++) {
data[i][j]= random.nextDouble();
}
}
//Add data to ObservableLists
for (int i = 0; i <data.length ; i++) {
observableLists.add(data[i]);
}
//Create Columns
for (int i = 0; i <data[0].length ; i++) {
TableColumn<double[], Double> column= null;
column = new TableColumn<>("column "+i);
int finalI = i;
column.setCellValueFactory(param -> new ReadOnlyObjectWrapper<>(param.getValue()[finalI]));
tableView.getColumns().add(column);
}
// Fill TableView
tableView.setItems(observableLists);
}
@Override
public void initialize(URL location, ResourceBundle resources) {
}
}

SideBar.fxml

<BorderPane fx:id="borderPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.SideBarController">
<left>
<VBox prefHeight="400.0" prefWidth="173.0" style="-fx-background-color: black;" BorderPane.alignment="CENTER">
<children>
<Button mnemonicParsing="false" onAction="#openPane1" prefHeight="25.0" prefWidth="177.0" style="-fx-background-color: blue; -fx-border-color: white;" text="Pane 1" textFill="WHITE">
<VBox.margin>
<Insets top="50.0" />
</VBox.margin>
<font>
<Font name="System Bold" size="17.0" />
</font>
</Button>
<Button mnemonicParsing="false" onAction="#openPane2" prefHeight="25.0" prefWidth="176.0" style="-fx-background-color: blue; -fx-border-color: white;" text="Pane 2" textFill="WHITE">
<VBox.margin>
<Insets top="10.0" />
</VBox.margin>
<font>
<Font name="System Bold" size="17.0" />
</font>
</Button>
</children>
</VBox>
</left>
<center>
<Pane prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER">
<children>
<Label layoutX="163.0" layoutY="152.0" prefHeight="68.0" prefWidth="131.0" text="Home">
<font>
<Font size="46.0" />
</font>
</Label>
</children>
</Pane>
</center>
</BorderPane>

Sample.fxml

<Pane prefHeight="395.0" prefWidth="597.0" style="-fx-background-color: white;" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
<children>
<TableView fx:id="tableView" layoutX="77.0" layoutY="47.0" prefHeight="266.0" prefWidth="461.0" />
<Button layoutX="257.0" layoutY="329.0" mnemonicParsing="false" onAction="#fillTable" text="fill Table" />
</children>
</Pane>

SecondFxml.fxml

<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1">
<children>
<Label layoutX="232.0" layoutY="153.0" text="Pane 2">
<font>
<Font size="46.0" />
</font>
</Label>
</children>
</Pane>

Do not reload from fxml when button is clicked. Do it once in initialize:

public class SideBarController implements Initializable {
@FXML BorderPane borderPane;
private Parent sample, secondFxml;
public void openPane1(ActionEvent event) throws Exception {
borderPane.setCenter(sample);
}
public void openPane2(ActionEvent event) throws Exception {
borderPane.setCenter(secondFxml);
}
private Parent loadScene(String sc) throws IOException {
return FXMLLoader.load(getClass().getResource(sc));
}
@Override
public void initialize(URL location, ResourceBundle resources) {
try {
sample = loadScene("Sample.fxml");
secondFxml =  loadScene("secondFxml.fxml");
} catch (IOException ex) {
ex.printStackTrace();
};
}
}