java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver when trying to connect an Android Studio app to oracle database via wallet

I'm pretty new to java and specially to android and i got stuck making a little project on my own so i'd be very glad someone could help me.

I'm trying to make my app connect to a free tier oracle database (19c) and despite having set the ojdbc8.jar driver inside app/libs I keep getting java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver.

I also searched several threads and none of the solutions has worked for me.

I don't want to purchase oracle mobile connector given that is just a test app to learn.

Here's my code.

import java.sql.*;

public class ConnectionToOracleDB {

    private static final String DEFAULT_DRIVER = "oracle.jdbc.driver.OracleDriver";
    private static final String DEFAULT_URL = "jdbc:oracle:thin:@dbmc_high...?TNSADMIN=(tnsnames location)";
    private static final String DEFAULT_USERNAME = "USER";
    private static final String DEFAULT_PASSWORD = "PASSWORD";

    private Connection connection;

    public void main() {
        try {
            this.connection = createConnection();
            Statement stmt=connection.createStatement();
            StringBuffer stringBuffer = new StringBuffer();
            ResultSet rs=stmt.executeQuery("select 1 from DUAL");
            while(rs.next()) {
                stringBuffer.append( rs.getString(1)+"\n");
            }
            System.out.println(stringBuffer.toString());
            connection.close();
        }
        catch (Exception e) {

            System.out.println(e);
        }
    }

    public static Connection createConnection(String driver, String url, String username, String password) throws ClassNotFoundException, SQLException {

        Class.forName(driver);
        return DriverManager.getConnection(url, username, password);
    }

}