JDBC Drivers and `Class.forName()`

The short version: stop using Class.forName(driverClass) to load JDBC -drivers. You don't need this, and haven't since Java 6. You arguably never -needed this.

This pattern appears all over the internet, and it's wrong.

Backstory

JDBC has more or less always provided two ways to set up Connection objects:

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Obtain them from a driver-provided DataSource class, which applications or - containers are expected to create for themselves.
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Obtain them by passing a URL to DriverManager.
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Most people start with the latter, since it's very straightforward to use. -However, DriverManager needs to be able to locate Driver subclasses, and -the JVM doesn't permit class enumeration at runtime.

In the original JDBC release, Driver subclasses were expected to register -themselves on load, similar to

public class ExampleDriver extends Driver {
-    static {
-        DriverManager.registerDriver(ExampleDriver.class);
-    }
-}
-

Obviously, applications can force drivers to load using -Class.forName(driverName), but this hasn't ever been the only way to do it. -DriverManager also provides a mechanism to load a set of named classes at -startup, -via the jdbc.drivers system property.

JDBC 4 Fixed That

JDBC 4, which came out with Java 6 in the Year of our Lord Two Thousand and -Six, also loads drivers using the service -provider -system, which requires no intervention at all from deployers or application -developers.

You don't need to write any code to load a JDBC 4 driver.

What's The Harm?

It's harmless in the immediate sense: forcing a driver to load immediately -before JDBC would load it itself has no additional side effects. However, it's -a pretty clear indicator that you've copied someone else's code without -thoroughly understanding what it does, which is a bad habit.

But What About My Database?

You don't need to worry about it. All of the following drivers support JDBC -4-style automatic discovery:

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PostgreSQL (since version 8.0-321, in 2007)
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Firebird (since version 2.2, in 2009)
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MySQL (since version 5.0, in 2005)
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H2 (since day 1, as far as I can tell)
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Derby/JavaDB (since version 10.2.1.6, in 2006)
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SQL Server (version unknown, because MSDN is archaeologically hostile)
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JDBC Drivers and Class.forName()

Backstory

JDBC 4 Fixed That

What's The Harm?

But What About My Database?

JDBC Drivers and `Class.forName()`