Frequently asked questions, or "the human Google"

I really like the JDeveloper Forum on OTN. I have a little desktop widget that uses RSS to show the latest posts as they come in. I read the forum almost like a Blog – it’s always interesting, informative, and helpful to see what issues people are grappling with; lots of times, I get new ideas to try by reading posts there. I also try to answer as many of the questions that come up as I can. Why? The forum was helpful to me starting out, and, personally, I’d like to see others be successful with JDeveloper and the marketplace for JDeveloper to grow – purely for selfish reasons. I’m a consultant, and the more potential customers use JDeveloper and Oracle stuff, the more potential customers for me and the company I work for.

As I read the posts, there are some that just come up over and over and over and over. Lots of times, I’ll answer the questions by doing a quick search on the forum and posting the link (hence “the human Google”). So I thought I’d compile a list of questions and answers here, sort of an unofficial FAQ. For what it’s worth, I mostly use ADF Business Components and ADF Faces – not much of an EJB/Swing guy at the moment, so don’t expect to see Swing/EJB questions.

By the way, if there’s a better answer somewhere or something that should be added, let me know and I’ll update the list – just post a comment to this entry.

Some of the questions/answers are a bit tongue-in-cheek

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Question: I’d like to create a page to frobdigate the whigginator. It’s urgent so please help me!

Answer: Would you now? Honestly, there are a fair number of questions on the forum that are about this comprehensible. If you want a good answer, be sure to provide enough information so that the readers at least know what you’re talking about.

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Question: When will version xyz of JDeveloper be available?

Answer: When it’s ready. I’ve been guilty of asking this question a few times myself.

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Question: How do I convert among java.util.Date and oracle.jbo.domain.Date and java.sql.Date

Answer: Here’s a good post that gives a few examples.

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Question: How can I create two drop-down list boxes (af:selectOneChoice) such that when I pick a value from the first one, it changes the values in the second one – for example, when I pick the State from the first, the second one should contain a list of cities in that state?

Answer: Frank Nimphius of Oracle has written about this.

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Question: I want to add security to my Faces application where I can validate the username and password against a database table. How do I do that?

Answer: Here’s one way.

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Question: blah blah blah OAF blah blah Oracle Applications Framework blah blah OA Framework?

Answer: Try the OA Framework forum on OTN.

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Question: I want to have a gap-less sequence number as the key for my table, how

Answer: No, you don’t.

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Question: but I wasn’t finished with my question yet.

Answer: Yes you were.

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Question: OK, I understand I should use a database sequence. Why is the number negative/how do I use the sequence?

Answer: Have a read of the ADF Developer’s Guide for Forms/4GL Developers, section 6.6.3.8 for starters. Then, read the rest of that document

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Question: How can I display images that are stored in a blob in the database?

Answer: Read this post

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Question: How can I use a drop-down list (af:selectOneChoice) inside of an editable table (af:table)?

Answer: Steve Muench of Oracle did a nice screencast showing how to do that.

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Question: How can I call a stored procedure from my application module code? I don’t want to open a new database connection

Answer: Check out this post.

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Question: I am trying to connect to my Oracle XE database and am getting errors. What do I need to do?

Answer: The Oracle XE connection information is localhost:1521:XE. Most likely, you forgot to change the SID from “ORCL” to “XE” when you set up the connection.

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Question: How do I get the selected label of an af:selectOneChoice? Every time I try, I just get a number

Answer: Frank Nimphius to the rescue again.

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Question: How do I highlight the selected row in an af:table?

Answer: Check out this post for a couple of answers.