SQLException : No current connection? Why ?

[freethinker]

Hi,

I have a database class I use to get and drop db connections:

public class Database {
    protected static Connection c;    
    //....
   /// .. c = DriverManager.getConnection ....
 
    public Connection getConnection() {
           return c;        
    }
    public void dropConnection() {
        try {
            c.close();
        } catch (SQLException ex) {
            System.err.println("SQLException: " + ex.getMessage());
        }
    }
}

All other methodes like updatePlayer, insertPlayer, getAllPlayers .. work very good. Only in this selectPlayer I get an error message:
SQLException : No current connection.

 
    ///...
    private Statement stmt;
    private Database db;
    private Connection con;
 
    public Player selectPlayer(int id) {
 
        if (this.db == null) {
            db = new Database();
        }
 
        Player p = new Player();
 
        String sql =
                "SELECT playerID, name, team FROM tblPlayer WHERE " +
                "playerID= " + id + "";
 
 
        try {
            con = db.getConnection();
            stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery(sql);
 
            while (rs.next()) {
                p.setPlayerID(rs.getInt("playerID"));
                p.setName(rs.getString("name"));
                p.setTeam(rs.getString("team"));
            }
        } catch (SQLException ex) {
            System.err.println("SQLException : " + ex.getMessage());
        }
        try {
            stmt.close();
        } catch (SQLException ex) {
            System.err.println("SQLException: " + ex.getMessage());
        } finally {
            db.dropConnection();
        }
        return p;
    }

Can u help? thx in advance
Kr,

[JosAH]

@freethinker
Somewhere in that code fragment setting up a connection fails and you probably muffle away any thrown exception. Were you able to load the driver?

kind regards,

Jos

[freethinker]

Hi, thanks.
Yes I am able to run the hole application to manage players, teams, matches, records, .. all things, all classes and all methodes except that one (selectPlayer) and all methodes to save data in all classes I use the same structure, and they all work perfect except that method in the class DataPlayer.

Kr,

[freethinker]

It is really bizarre, because when I debug, and get into these lines:

con = db.getConnection(); 
stmt = con.createStatement(); 
ResultSet rs = stmt.executeQuery(sql); 

con = db.getConnection(); => This works, I get into my database class, and the methode getConnection returns variable c without any problem.

And here:
stmt = con.createStatement(); ==> It throws exception wich i catch with System.out.println(), on the scree I read: SQLException : No current connection.

[JosAH]

System.out.println() is your friend: what is the value of 'con'?

kind regards,

Jos

[freethinker]

@JosAH
con = (org.apache.derby.impl.jdbc.EmbedConnection40) #2003

Kr,

[freethinker]

But I see a difference between con values, to comapre:

[JosAH]

Let's dissect this nasty little problem:

1) were you able to load your data from the database?
2) did you close that connection somewhere? (you should reset that connection to null after closing).

kind regards,

Jos

[freethinker]

@JosAH
Yes

2) did you close that connection somewhere?

Ofcourse I close it after every SQL statement in the finally block.

(you should reset that connection to null after closing).

You mean con= null and then con.close() ?
I don't have to do that for other methodes which

Thanks.

[freethinker]

I solved it, but with a bizarre solution :)
I just have to recall the constructor of DataPlayer, even after doing this in the constructor of UI class.

Example: (see line 10, 18 and 32)

public class PlayerPanel extends JPanel { 
 
    private ArrayList<Player> pList;
    private DataPlayer dp;
    private Player p;
    private int identifier = 1;
 
    public PlayerPanel () {
        setLayout(null);
        dp = new DataPlayer();
        p = new Player();
 
        viewPlayers();
        selectPlayer();
    }
 
    public void viewPlayers() {
        dp = new DataPlayer(); // this is what I have to add
        p = new Player();
 
        list.removeAll();
        pList= new ArrayList<Player>();
        pList = dp.selectAllPlayers();
        for (Player player : pList) {
            list.add(p.toString());
        }
 
 
    }
 
    public void selectPlayer() {
       dp = new DataPlayer(); // this is what I have to add
        /....
 
        p = dp.selectPlayer(identifier);
 
       /..
    }
 
      }
}