Question

AppletContext is lost; URL not working

Asked by: polina

I am using showDocument() to connect to a different
URL from inside of my applet.
However if I go to a different Web site from the browser session where my applet is running the URL link is not working anymore.
I am getting NullPointer on AppletContext since environment has changed. How can I fix that?

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Asked On
2001-11-06 at 10:25:56ID20227862
Tags

appletcontext

,

nullpointer

,

working

Topic

Java Programming Language

Participating Experts
5
Points
100
Comments
14

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Answers

 

by: sgomsPosted on 2001-11-06 at 13:11:03ID: 6623198

check out the example in http://java.sun.com/docs/books/tutorial/applet/appletsonly/browser.html

this example allows u to go to any URL you wish to.

 

by: objectsPosted on 2001-11-06 at 15:52:48ID: 6623511

Not sure I understand what your problem is.
Can you post the relevant parts of your code.

 

by: heyhey_Posted on 2001-11-07 at 01:50:06ID: 6624204

> I am getting NullPointer on AppletContext since environment has changed. How can I fix that?
         

when your applet is destroyed, it's AppletContext will be set to null and you cannot use it any more.

 

by: objectsPosted on 2001-11-07 at 02:22:13ID: 6624255

Specify a target in your showDocument() call so that the new page is opened in a different window.

 

by: polinaPosted on 2001-11-07 at 05:29:15ID: 6624590

None of offered comments works for me.
I am giving more details.
I start IE and load my applet - applet1.
Within this applet there is an URL link:
try {
     URL u = new URL(sURL);
     URLConnection uconn = u.openConnection();
     Object content = uconn.getContent();
     myMain.pPasswordDialog.sApplet.myAppletContext.showDocument(u, "_blank");
 }
   catch (MalformedURLException e) {}
   catch (IOException e) {}

Here a long string "myMain.pPasswordDialog....." is just a reference to an Applet class where the expression:
myAppletContext = getAppletContext();
resides.
This link works fine untill I try to switch to a different
website from the one where my applet1 is running.
It does not affect my applet1 - it runs fine (it is not
destroyed); however the URL link is not working anymore.
                 

 

by: heyhey_Posted on 2001-11-07 at 05:37:25ID: 6624610

> It does not affect my applet1 - it runs fine (it is not
destroyed);

applet1 is destroyed - i.e. it's destroy() method is called and it's context is set to null.

 

by: objectsPosted on 2001-11-07 at 13:37:38ID: 6625865

> however the URL link is not working anymore

Can you describe exactly how it's not working.
Are you getting any exceptions?

 

by: polinaPosted on 2001-11-08 at 05:27:56ID: 6627243

No, I am not getting any exception;
When I had getAppletContext().showDocument()
in that long line, I was getting NullPointerException
on AppletContext; then I replaced it with the myAppletContext (the result of the getAppletContext() in
Applet class). Now it does nothing at all; on ActionPerformed it comes to that URL link and stops.
I assume that AppletContext has changed when I leave the page; I don't know how to restore/save it. As I said at the same time the parent apllet1 is not effected; it is functioning fine.

 

by: objectsPosted on 2001-11-08 at 13:45:23ID: 6627697

You problem maty be related to the following:

URL u = new URL(sURL);
URLConnection uconn = u.openConnection();
Object content = uconn.getContent();
myMain.pPasswordDialog.sApplet.myAppletContext.showDocument(u, "_blank");

You don't think you need the middle two lines, you just need:  

URL u = new URL(sURL);
myMain.pPasswordDialog.sApplet.myAppletContext.showDocument(u, "_blank");

 

by: polinaPosted on 2001-11-14 at 04:13:46ID: 6631079

I've tried deleting these two lines.
That did not change the behaviour of the URL link;
it works as long as web page for the main applet stays;
as soon as you leave it URL link stops working.

 

by: heyhey_Posted on 2001-11-14 at 04:49:36ID: 6631164

> as soon as you leave it URL link stops working.

tha's NORMAL behaviour.
as soon as your applet is destryed it shouldn't be able to interact with the 'real world'.

 

by: objectsPosted on 2001-11-14 at 13:59:46ID: 6633246

Yes, it sounds like the applet reference that you're using to display the page is no longer available.

myMain.pPasswordDialog.sApplet

Is this the same applet that is currently executing, or is it a different one.
And if so, why aren't you simply using the current applet?

 

by: girionisPosted on 2003-05-07 at 09:15:13ID: 8481016

No comment has been added lately, so it's time to clean up this TA.

I will leave a recommendation in the Cleanup topic area that this question is:

- points to heyhey_ (11/07/2001 01:50AM PST)

Please leave any comments here within the
next seven days.

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER !

girionis
Cleanup Volunteer

 

by: ChmodPosted on 2003-05-31 at 14:38:47ID: 8621579

As recommended

Chmod
Community Support Moderator @Experts Exchange

20120131-EE-VQP-002

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