Java Database Connectivity (JDBC)

Hello,

I'm using ODBCS with a JavaFx application.

The application works fine when i start it ... but when i leave it open for a while and then try to save something it raises this error:

java.sql.SQLRecoverableException: Closed Connection
    at oracle.jdbc.driver.PhysicalConnection.getAutoCommit(PhysicalConnection.java:4337)
    at oracle.jdbc.driver.PhysicalConnection.rollback(PhysicalConnection.java:4507)
    at model.Database.rollback(Database.java:95)
    at viewcontroller.main.MainPageController$2.call(MainPageController.java:569)
    at viewcontroller.main.MainPageController$2.call(MainPageController.java:481)
    at javafx.concurrent.Task$TaskCallable.call(Task.java:1423)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.lang.Thread.run(Thread.java:748)

This issue only happens when connecting to the ODBCS ... when i test the application with my the XE database on my laptop it works fine.

So why am i getting this error? and please how can i fix it?

This is my Database connection class:
private static final String username = ******
    private static final String password = *******
    private static final String connString = "jdbc:oracle:thin:@localhost:1521:xe";
    private static Connection conn;    
    
    private static Database instanse = new Database();
    
    private Database(){        
            System.out.println("Databse loading ..");
                    try {
                        if(conn==null){                  
                        setconnection();
                        }
                    } catch (SQLException | ClassNotFoundException ex) {
                        Logger.getLogger(Database.class.getName()).log(Level.SEVERE, null, ex);
                    }          
    }    
    
    public static Database getInstance(){
        if(instanse == null){                
            instanse = new Database();
        }
        return instanse;
    }
    
    public void setconnection() throws SQLException, ClassNotFoundException {
        OracleDataSource ds = new OracleDataSource();
        ds.setURL(connString);
        ds.setUser(username);
        ds.setPassword(password);
        conn = ds.getConnection();
        conn.setAutoCommit(false);
    }   
    
    public Connection getDbConn(){
        getInstance();
        return conn;
    }

Thank you

Gado