method doesnt work when invoked from applet!

[H Melua]

Hello

Let me tell you what I've done so far... I've got an applet class and a class that deals with database queries...(both combile without problem)

public class ItemApplet extends Applet implements ActionListener{
    ....
    public void actionPerformed(ActionEvent e){
        if( e.getSource() == addButton){
            ....
            ItemsDB.add(); //the problem is here
        }
    }
}
 
public class ItemsDB{   
    public static add() throws SQLException, ClassNotFoundException{
    //the code here works fine...
    }
}

When i call the ItemDB.add() method from the applet, it doesnt work (nothing happens! & the item isnt added)...

can someone please suggest a solution?

thank you
Hannah
[ January 04, 2006: Message edited by: H Melua ]

[Ulf Dittmer]

So I guess when you say "the code here works fine", what you really mean is: "the code here doesn't work fine"

It's hard to say what code you don't show us might or might not be doing. But the combination of applets and databases suggest two possible problems, both related to the restricted privileges of applets:
- the DB host is not accessible to the applet (because applets can only connect to the host where they were served from)
- the driver classes are not part of the applet (or use native libraries), and so the driver can't instantiate them

You can information on how to work around these issues here.

If it's neither of these, you can post the relevant code with an indication of where it fails to execute properly.

[H Melua]

it works because i tried it and it added a record to the database with no reported problems

i'll check your link and get back to you

here it is

     public static add() throws SQLException, ClassNotFoundException{
            int count = 0;
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            String url = "jdbc: odbc:Items";
            con = DriverManager.getConnection(url) ;
            stmt = con.createStatement();
            count = stmt.executeUpdate("INSERT INTO Items " +
                "(ItemDescription, ItemPrice, ItemExpiryDate) " + 
                "VALUES ('Beans small can', '12.1', '12/12/2000')") ;
            System.out.println ("\nInserted " + count + " record(s) successfully\n") ;
            con.close();
    }

thank you
Hannah
[ January 04, 2006: Message edited by: H Melua ]

[H Melua]

Ok i've seen the policy file, but what do i change in particuler?
[ January 04, 2006: Message edited by: H Melua ]

[Ulf Dittmer]

Adding something like the following should do the trick:

grant codeBase "http://YOUR.SERVER.HERE/PATH.TO.YOUR.APPLET.HERE/-" {
   permission java.net.SocketPermission "*", "connect, listen, resolve";
   permission java.lang.RuntimePermission "*";
};

[H Melua]

http://YOUR.SERVER.HERE

i dont know the value for this

[Ulf Dittmer]

Something like "www.mycompany.com", or "localhost:8080", or whereever the applet is hosted.
[ January 04, 2006: Message edited by: Ulf Dittmer ]

[H Melua]

i dont know the value for this

in english, where do i find it?
thanks

[Ulf Dittmer]

How do you access the applet if you don't know what server it's hosted on? How do you upload it?
[ January 04, 2006: Message edited by: Ulf Dittmer ]

[H Melua]

you see, i use BlueJ and by creating an applet class, i write click on the class object and choose "Run Applet", i get these options
(blueJ if u havnt tried it is an educational java tool supported by Sun, works differently to JBuilder and Jgrasp
http://images.apple.com/downloads/macosx/development_tools/images/bluej130_screen.jpg)

- Generate webpage only
- Run applet in appletviewer [thats what i choose]
- Run applet in web browser

!

in the appletviewer, there is an Applet menu>>>>Properties>>>>
- http Proxy server (with an empty field)
- http proxy port ('80')
- Class access (option- 'Restricted'/'Unrestricted')
(Command buttons 'Apply', 'Reset' & 'Cancel'

it was on restricted, but now i changed it, and i dont know if it will make any difference, because i'm still debugging my code, so i havnt checked!
[ January 04, 2006: Message edited by: H Melua ]

[Ulf Dittmer]

In that case, if you run the applet locally in your browser, make a note of the URL you see there. It should be something like "file:///path/to/directory/index.html". Then you can use "file:///path/to/directory/-" instead of "http://YOUR.SERVER.HERE/PATH.TO.YOUR.APPLET.HERE/-". Just remember to add the proper policy for the server later.

[Jeanne Boyarsky]

Moving to applet forum now that we are discussing policies.