How to display Column Headers from a Mysql database in JavaFX TableView?

Let me clarify the question. So I decided to create a TreeView just like in PhpMyAdmin (xampp) that shows all Databases. I successfully managed to get the Databases and Tables in the Treeview, but not the content of the Tables in the TableView. So basically the first thing I want to do is, that if I click on a Table, the column headers should show up in the Table next to the Treeview. I managed to write some code, but it does not do what it is supposed to do. Please help me I am trying to learn this programming language (JavaFX).

This is the Controller class

package sample;

import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.control.cell.PropertyValueFactory;
import java.net.URL;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ResourceBundle;

public class Controller implements Initializable {

    Statement statement;
    Statement statementDatabase;
    Statement stmntTables;
    Statement stmntUse;
    Statement stmntCols;
    ResultSet resultDatabase;
    ResultSet resultTables;
    ResultSet resultUse;
    ResultSet resultCols;
    
    @FXML
    TreeView <String> treeView;
    @FXML
    TableView<String> tableView;

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {

        try {
            statement = DatabaseConnection.getInstance().getConnection().createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
            ResultSet result = statement.executeQuery("SHOW DATABASES");

            TreeItem<String> root = new TreeItem<>("Datenbanken");

            while(result.next()) {
                TreeItem<String> node = new TreeItem<>(result.getString(1));
                root.getChildren().add(node);

                Statement statement2 = DatabaseConnection.getInstance().getConnection().createStatement();
                ResultSet subResult = statement2.executeQuery("SHOW TABLES FROM " + result.getString(1));
                while(subResult.next())
                {
                    TreeItem<String> node2 = new TreeItem<>(subResult.getString(1));
                    node.getChildren().add(node2);
                }
            }
            result.beforeFirst();
            treeView.setRoot(root);
            root.setExpanded(true);
            
            ShowDatabase();
            UseDatabase();

        } catch (Exception e){
            e.printStackTrace();
        }
    }
    
    
    public void ShowDatabase() {
        try {
            statementDatabase = DatabaseConnection.getInstance().getConnection().createStatement();
            resultDatabase = statementDatabase.executeQuery("SHOW DATABASES");
            System.out.println("All Databases displayed!");
        } catch (SQLException e) {
            System.out.println("Databases could not be displayed!");
            e.printStackTrace();
        }
    }

    public void UseDatabase() {
        try {
            while (resultDatabase.next()) {
                stmntUse = DatabaseConnection.getInstance().getConnection().createStatement();
                resultUse = stmntUse.executeQuery("USE " + resultDatabase.getString(1));
                //System.out.println(resultDatabase.getString(1));
                ShowTables();
                //System.out.println(resultTables.getString(1));
                ShowColumns();
            }
            System.out.println("Database injected!");
            System.out.println("All Tables displayed!");
            System.out.println("All Columns displayed!");
        } catch (SQLException e) {
            System.out.println("Database ejected!");
            e.printStackTrace();
        }
    }

    public void ShowTables() {
        try {
            while (resultDatabase.next()) {
                stmntTables =  DatabaseConnection.getInstance().getConnection().createStatement();
                // System.out.println(resultDatabase);
                resultTables = stmntTables.executeQuery("SHOW TABLES FROM " + resultDatabase.getString(1));
                // System.out.println(resultTables.getString(1));
            }
        } catch (SQLException e) {
            System.out.println("Tables could not be displayed!");
            e.printStackTrace();
        }
    }
    
    public void ShowColumns() {
        try {
            while (resultTables.next()) {
                stmntCols =  DatabaseConnection.getInstance().getConnection().createStatement();
                resultCols = stmntCols.executeQuery("SHOW COLUMNS FROM " + resultTables.getString(1));
                System.out.println(resultCols);
                FillTable(resultCols);
    
            }
        } catch (SQLException e) {
            System.out.println("Columns could not be displayed!");
            e.printStackTrace();
        }
    }
    
    public void FillTable(ResultSet res) {
        TableColumn<String, String>col = new TableColumn<String, String>();
        try {
            col.setCellValueFactory(new PropertyValueFactory<>(res.getString(1)));
        } catch (SQLException e) {
            e.printStackTrace();
        }
        tableView.getColumns().add(col);
    }
}

and this is the Database Connection

package sample;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;


public class DatabaseConnection {

    private static DatabaseConnection instance;
    private Connection connection;
    private static String ip = "localhost";

    public static void setIp(String ip) {
        DatabaseConnection.ip = ip;
    }

    private DatabaseConnection() throws SQLException
    {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            connection = DriverManager.getConnection("jdbc:mysql://" + ip + ":" + 3306, "root", "");
            System.out.println("Successfully connected to " + ip + "!");

        } catch (Exception exc) {
            //exc.printStackTrace();
            System.out.println("Connection failed to " + ip + "!");
            getConnection().close();
        }
    }

    public Connection getConnection() {
        return connection;
    }

    public static DatabaseConnection getInstance() throws SQLException {
        if (instance == null) {
            instance = new DatabaseConnection();
        } else if (instance.getConnection().isClosed()) {
            instance = new DatabaseConnection();
        }
        return instance;
    }

}