programmatically checking for open connection in JDBC

Question

How do I check for an open connection in jdbc for oracle database?

Note: conn.isClosed() cannot be used for this.

Answer 1

Usually a Connection Pool will also use the Connection.isClosed() method to check if the Connection is still valid. The problem is that not all JDBC drivers will handle this call correctly. So I assume that there are some simple check statements just like RealHowTo said. For Oracle he already mentioned the "SELECT 1 FROM Dual" which should succeed always for Oracle databases. I think that there are similar queries for the different database. I can remember that in a previous project we also implemented an own Connection Pool which used such validation queries.