K. Tsang is right about not using the JDBC-ODBC bridge. You can find links to JDBC drivers for Oracle at our
Oracle FAQ. I'd suggest switching to Oracle driver immediately, it will save you a lot of trouble.
Unfortunately, I don't see a clear problem in your code. It does look like a forgotten commit, but autocommit is the default in JDBC, so it probably isn't the reason. Are you sure you're looking into the right table in SQL Developer?
I have a few lesser points, though:
1) You're using the SYSTEM account for your application. It is not a good practice. In real environment, it is outright impossible, as it would bring terrible security issues. But even for small learning project it is not appropriate (you might run into issues allocating too much space in the SYSTEM tablespace, for example). The best is to learn from your first day that SYSTEM is just for administering the database. You need to learn how to create users (look up the CREATE USER command in Oracle documentation) and grant them necessary privileges (the GRANT command). You'll do this using your SYSTEM account, but then you'll use the newly created user in your application.
If you don't know how to start, try
this book. It doesn't teach you to create a new account, just to unlock and use an existing one, but still far better than using SYSTEM. And perhaps it might be useful to you for other reasons as well.
2) Learn how to use
PreparedStatements. All of the reasons mentioned in the article apply fully to Oracle database.
3) Specify target column in the
insert into statement (here is
why).
4) The
Avoid Implicit Conversions advice applies to your case as well. (If you start using PreparedStatement, this will be less of a concern probably.)
Neither of these are connected to your current problem, but the sooner you get used to these practices, the better for you.