Java javac compile with classpath

I was wondering if it's possible to include a jar in the classpath when compiling instead of executing. At the moment I am just checking to see if my PostgreSQL driver can be found

everything is in the same location for testing purposes so

program/
    DriverCheck.java
    DriverCheck.class
    postgresql-longassname.jar

DriverCheck.java contains

public class DriverCheck {

    public static void main(String[] args) {

        try {
            Class.forName("org.postgresql.Driver");
            System.out.println(Driver Found);
        } catch(Exception log) {
            System.out.println(Driver Not Found);
        }

    }

}

If I compile and execute this as normal

# javac DriverCheck.java

# java -cp ".:./postgresql-longassname.jar" DriverCheck

It works as I get the output

Driver Found

However if I try to compile and execute in this manner

# javac -cp ".:./postgresql-longassname.jar" DriverCheck.java

# java DriverCheck

It does not work as I get the output

Driver Not Found

Why is this and is there a way for me to use the second method for including jars?