How to do this ???

Bear in mind this is RDBMS-specific. It's possible in Oracle, but necessarily so with other DBs

Hi nicolle,

If your SQL server has this kind of feature, you won't be able to use it with Java.
But you can build a SQL filter server :
Instead of:
  SQL client application  <->  SQL Server
You can do:
  SQL client application  <->  SQL filter server  <->  SQL Server
The SQL filter server should detect any modification query on tables and notify your application (using Socket for example) if the query is successfull.

Most probably you can't do it.
what database are you using?

CHEJ,

After I set a trigger in SQL server to call the java, how do I raise the event ?

Sorry nicolle - somehow i managed to miss you're using SQL Server - hence the general nature of my comment ;-)

You can use triggers with SQL Server, but afaik it does not support calling Java code (and I very much doubt it would).

I see ! The reason I want to raise an event when a row is added or deleted in java is to learn how to implement the event handling. Maybe I should change it to the following:

Monitor on a directory to detect if a file is added or deleted:

public synchronized void fileChangedEvent(some kind of event list)
{
  switch (event list)
  {
    case add:
            Do something.
    case delete:
            Do something.
  }
}

http://java.sun.com/docs/books/tutorial/uiswing/events/index.html

>>Monitor on a directory to detect if a file is added or deleted:

Yes, you could do this by polling the directory every n milliseconds and then raise a custom event that can be broadcast to listeners when changes are detected

Theres no need for implementing generating your own events for learning about event handling. Swing is event based so is well suited for learning about event handling. See the above link for more details.

I think I like CEHJ proposed.

CEHJ,

Can you give more detail for how to do it ? Thanks !

The code snippet u posted above suggests you want to *listen* for events and take relevant action.
Is this correct or do you want to know how to *generate* events?

objects,

You are right ! I would like to listen for some events. When one of the event occurs, the code should
take action based on that event. Is the url you have posted will help me ?

Both the URL's I posted should help you.

It's not really clear what you want:

>>is to learn how to implement the event handling.

>>I would like to listen for some events

suggests two related, but different, things really. If it's just the second one you want to do

JButton b = new JButton("Click me!");
b.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
            System.out.println("I've been clicked");
      }
});

will fit the bill. You are listening for events on the button.

It you want to study how event handling is *implemented* the best way is to create your own events as you will then need to work through each element in the event handling mechanism, including how listeners are added, how they are notified, etc.

> You are listening for events on the button.

Which is covered in the link I posted earlier.

And creating event is covered in the second link I posted.

The second link is a relatively complex example with little commentary. This outlines the mechanisms involved in custom events much more clearly:

http://www.javaworld.com/javaworld/javaqa/2002-03/01-qa-0315-happyevent.html

Except that nicolle has stated that the interest is in *listening* for events :)
For which Swing is a perfect example to learn from.

Let me look at both. Thanks !

In VB, when a program is terminated, a form_unload event will be invoked.

Is there such thing in Java ? How do I create this event ? If possible I would like to modify object's posting (code) and to have this unload event.

for a GUI application you would listen for WindowEvent's when the window was closed.
What exactly is it u want to do?

Listen for the WindowClosing event see

http://javaalmanac.com/egs/java.awt/frame_FrameCls.html

I just want to modify the adding/deleting file detection code into windows service application.
I am using free 3rd party jar library to make it into service.

Unfortunately, it is a console application. Thus, there is no windowEvent. I just want to receive an email when someone is closing the app.

Most importantly, I want to turn off some resources if the app is terminating.

> I am using free 3rd party jar library to make it into service.
>  I want to turn off some resources if the app is terminating.

you should clean up when the service is stopped.

CEHJ,

Thansk ! I think addShutdownHook is very useful to do some action before terminating the app.

> I think addShutdownHook is very useful to do some action before terminating the app.

Use with care though thats not what they are really intended for.

Thanks for the points :)

http://www.objects.com.au/staff/mick

8-)

>>Use with care though thats not what they are really intended for.

True. If you want to be more precise, use your main class' finalize