Question

I have defined a variable with

Object[] data;

How can I fill it up with data in the next step?

I want to do something like this:

    public Object[] select() {
   Object[] data; // Here I definded it
    try {
        stmt = conn.createStatement();
        rs = stmt.executeQuery("SELECT * FROM CUSTOMERS");
        while (rs.next()) {

/* data = {(rs.getString("fname"), (rs.getString("lname")); */
// I know it's wrong, but how can I fill it with data from a database?

        }
        rs.close();
        stmt.close();
    } catch (SQLException ex) {
        System.out.println("error while selecting");
        System.err.println(ex);
    }
    return data;
}


// -----
// somewhere else
model.addRow(DB.INSTANCE.select());

Answer 1

It’s

 data[i++] = new Object[] {rs.getString("fname"), rs.getString("lname")}; 

But frankly I’d look at the option of creating a new class. I even have a fancy name for it: Customer.

So that your main cycle would look like that:

 while (rs.next()) {
     data[i++] = new Customer(rs.getString("fname"), s.getString("lname"));
 }

Now you may ask what’s i and how do we create the data in the first place? All good questions. You don’t know beforehand how long the result set is going to be, so arrays are not a good idea. Try using List instead:

public List<Customer> select() {
    List<Customer> data = new ArrayList<Customer>(); // Here you define it
    // some code
        while (rs.next()) {
            data.add(new Customer(rs.getString("fname"), (s.getString("lname")));
        }
    // etc.
    return data;
}

Note that you can almost read it aloud: data, add a new Customer, please.

Finally, I highly recommend you to take a look at the finally keyword: it will save you time otherwise spent on strange and intermittent bugs.

Hope that helps.