Java + BD method that returns me the num. characters that are there [duplicated]

My problem is this, I have a BD and a Java application, we forgot the BD, let's focus on the App, I created a connection to a database that SI works, very all right. Now I propose to create a method in JAVA that returns an integer, the problem that arises is

  

Exception in thread "main" java.lang.NullPointerException at   Conexion.Conexion.contar_num_personajes (Conexion.java:58) at   Test.Test.main (Test.java:34)

I have looked and should not give me that, it is something I am new to and I strive to learn every day more, it gives me the exception of NullPointer

package Conexion;

import com.mysql.jdbc.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Conexion {

    private Connection co;

    public Conexion() {
        this.co = null;
    }

    public Connection get_conection() {
        return this.co;

    }

    public boolean conectar() throws ClassNotFoundException, SQLException {
        /*
         Connection c = null;
         Class.forName("com.mysql.jdbc.Driver");
         //el metodo getConnection() hay que adaptarlo para conectarlo a mi base de daots de hostinguer
         c = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306//");
         Statement stm = c.createStatement();
         System.out.println("Conectado correctamente a la Base de Datos de 'League Of Leguends'");
         this.co = c;

         */
        boolean conectado = false;
        Connection c = null;
        Class.forName("com.mysql.jdbc.Driver");
        c = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/LEAGUE_OF_LEGENDS", "miusuario", "micontraseña");
        Statement stm = c.createStatement();
        conectado = true;
        System.out.println("Conectado correctamente a la Base de datos : LEAGUE OF LEGUENDS");

        if (conectado == true) {
            return true;
        } else {
            return false;
        }


    }

    public int contar_num_personajes() throws SQLException {
        int n = 0;
         Connection dbConnection = get_conection();
        Statement stm = dbConnection.createStatement();
        // almaceno resultado de consulta en ResultSet
        ResultSet rs = stm.executeQuery("SELECT count(*) FROM personajes");
        // chequeo que el result set no sea vacío, moviendo el cursor a la 
        // primer fila. (El cursor inicia antes de la primer fila)
        if (rs.next()) {
            //Si hay resultados obtengo el valor. 
            n = rs.getInt(1);
        }
        // libero recursos
        stm.close();
        dbConnection.close();
        return n;
    }
}