Подключение к SQLite

Код:

package sqlite;
import java.sql.*;
import java.util.Scanner;
public class Programm{
    public static void main (String [] args) {
        Programm bd = new Programm();
        bd.open();
        bd.create();
        bd.insert();
        bd.close();
    }
    Connection co;
    void open() {
        try {
            Class.forName("org.sqlite.JDBC");
            Connection co = DriverManager.getConnection("jdbc:sqlite:track.db");
            System.out.println("Connected");
        }catch(Exception e) {
            System.out.println(e.getMessage());
        }
    }
    void create() {
        try {
        Statement statement = co.createStatement();
        String query = 
                "CREATE TABLE if not exists 'track_data' ( "+
                        "TIME_IN_MS DOUBLE PRECISION, " +
                        "EKG1 DOUBLE PRECISION); ";
        statement.execute(query);
        System.out.println("Таблица создана или уже существует.");
        }catch(Exception e) {
            System.out.println(e.getMessage());
        }
    }
    void insert() {
        try {
        Scanner sc = new Scanner(System.in);
        double time = 2;
        double ekg_1 = 3;
        String query = "INSERT INTO tracks (TIME_IN_MS, EKG1) " +
                "VALUES ('" + time +"','"+ ekg_1+"')";
        Statement statement = co.createStatement();
        statement.executeUpdate(query);
        System.out.println("Rows added");
        }catch(Exception e) {
            System.out.println(e.getMessage());
        }
    }
    void close() {
        try {
            co.close();
        }catch(Exception e) {
            System.out.println(e.getMessage());
        }
    }
}

Результат:

Connected null null null

Что я не так понимаю?