Addition image to database java

Question

I have such a problem, I have a class for working with a database, but since I am not familiar with java, I have a problem with adding an image to the database. If in c# I would simply create an array of bytes and add it to the line, then here I don’t know how this can be implemented.

Example create sql line in c#

string sqlLine = $"insert .... values({bytes})"

Class DataBase in java

Method command is responsible for sending the command to the database, the cmd argument is just the same sql query.

package Models;

import java.sql.*;
import java.util.ArrayList;

public class DataBase {

    // url connection
    private final String url = "jdbc:sqlite:----";
    private Connection connection = null;
    private ResultSet resultSet = null;
    private Statement statement = null;
    private ArrayList<ArrayList<String>> info = null;

    /*
     *  Database connection
     *  Param = none
     *  Return = none
     * */
    private void connectionOpen()
    {
        try {
            connection = DriverManager.getConnection(url);
        }
        catch (SQLException ex){
            connection = null;
        }
    }

    /*
     *  Closing the database connection
     *  Param - None
     *  Return - None
     * */
    private void connectionClose() throws SQLException
    {
        if(connection != null) {

            connection.close();
            connection = null;
        }
    }

    public Connection getConnection() { return connection; }

    private void writeDataToList() throws SQLException {
        info = new ArrayList<ArrayList<String>>();
        ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
        final int ColumnCount = resultSetMetaData.getColumnCount();

        while (resultSet.next()) {
            ArrayList<String> temp = new ArrayList<>();
            for (int j = 1; j <= ColumnCount; j++)
                temp.add(resultSet.getString(j));
            info.add(temp);
        }
    }

    /*
     *  Sending sql query to database
     *  Param - cmd (sql request)
     *  Return - ArrayList<ArrayList<String>>
     * */
    public ArrayList<ArrayList<String>> command(String cmd) throws SQLException {
        return command(cmd, CommandType.Another);
    }

    public ArrayList<ArrayList<String>> command(String cmd, CommandType type) throws SQLException {

        connectionOpen();

        if(connection != null) {

            try {

                statement = connection.createStatement();
                resultSet = statement.executeQuery(cmd);

                if(type == CommandType.Select) {

                    writeDataToList();
                }
                
            } catch (SQLException ex) {
                System.out.println(ex.getMessage());

            } finally {
                try {
                    resultSet.close();
                } catch (Exception e) { /* Ignored */ }
                try {
                    statement.close();
                } catch (Exception e) { /* Ignored */ }
                try {
                    connectionClose();
                } catch (Exception e) { /* Ignored */ }
            }
        }else
            throw new SQLException("Failed connection");

        return info;
    }

    public enum CommandType{
        Select, Another
    }
}

I tried to create a sql query using PreparedStatement, but the problem is that you can’t get the connection variable from outside, and I can’t figure out how to correctly form a method that would generate this query.