Connection In Java

[SaraHrry]

Is it a good programming practice to open a connection to the database in a constructor in Java.

Please advise.

[Supamagier]

Better move it to a method, like 'openConnection(database)'.
It's cleaner.

[Tolls]

Generally (and there are always exceptions, so do not take this is a hard and fast rule) connections should be opened and closed in the shortest window possible, to do their job. So opening one in a constructor for use over an unspecified period of time isn't usually a good idea.

The specifics of your situation may change this, but it's unlikely.

[AndreB]

tolls, can you explain this issue? why it is bad to maintain a connection the whole time?

[FON]

Listen to Tolls suggestion.

You have to think about situation when very large number of users
need a DB connection at the same time - and you db driver supports
let's say 125 open connection in some short period of time.
You don't want them to wait for some other lazy user to finish his work
and close his connection.

So, create a separate ConnectionCreator class with methods for
connection creation and closing and be sure you use finally{} block
to close your connections in every method you work with them.

Nicely define your app methods and enclose your logic between open() and close() of db connections.

Takes some time and good practice to clear this things in your head.

regards

[Tolls]

In addition to what FON says, there is the flip side in that connections do not remain open indefintely. They timeout (based on db settings, or driver settings). Consequently you'd have to stick in "connection repair" code in to ensure your single connection is maintained.

[AndreB]

ty,
i recently took a look to my serverstatus ... with hundreds open connections :-)

thanks for the tip

[JosAH]

There is a small disadvantage if you close your Connection a.s.a.p. you lose your PreparedStatements when you close your Connection. A ConnectionPool that keeps your Connections alive keeps your PreparedStatements open but then again it leaves the Connection open as well.

kind regards,

Jos