NOTIFY/LISTEN with JDBC

Hi there,

I'm writing a database application in Java, which needs to get
notified about changes in the database. Therefore I'd like to use the
NOTIFY/LISTEN mechanism, but I can't get it working with JDBC. I
was told, to use connection.getWarnings() method to retrieve
notifications, which doesn't seem to work. I'm using PostgreSQL
6.5.1 with the JDBC-Driver 6.5 for jdk1.1, and the following code
doesn't produce any output, while a parallel running psql-shell
displays the notifications...

Connection c = DriverManager.getConnection(...);
Statement s = c.createStatement();
s.execute("LISTEN test");

while(true) {
s.execute("NOTIFY test");
SQLWarning w = c.getWarnings();
if (w != null)
System.out.println(w.getMessage());
try {
Thread.sleep(2000);
} catch (InterruptedException ex) {}
}

Am I doing something wrong?
Thanks a lot for your help,

Martin Kresse