Invoking Later, But Only Once

[drcode]

Hi, I'm writing a program where multiple operations may run that affect
the gui:

if(foo){
dostuff();
SwingUtilites.invokeLater(UpdateGui());
}
if(bar){
dostuff();
SwingUtilites.invokeLater(UpdateGui());
}
if(baz){
dostuff();
SwingUtilites.invokeLater(UpdateGui());
}

This might cause multiple GUI update operations to be placed on the
queue- However, I only need my GUI to be update once- Basically, if an
update is already on the queue, I want it to not bother placing another
one on there.

Clearly, there are ways to handle this programatically (have the GUI
event check if any modifications have happened since the last update)-
But I was wondering if there was a more "Javaish" way to post an event
to be executed, but not if it's already on the event queue?

Thanks for any tips!

Conrad Barski, M.D.

 

[Andrey Kuznetsov]

the gui:

if(foo){
dostuff();
SwingUtilites.invokeLater(UpdateGui());
}
if(bar){
dostuff();
SwingUtilites.invokeLater(UpdateGui());
}
if(baz){
dostuff();
SwingUtilites.invokeLater(UpdateGui());
}

This might cause multiple GUI update operations to be placed on the
queue- However, I only need my GUI to be update once- Basically, if an
update is already on the queue, I want it to not bother placing another
one on there.

int count;

public void addUpdate() {
count++;
SwingUtilites.invokeLater(UpdateGui());
}

public void doUpdate() {
if(count > 0) {
count = 0;
UpdateGui();
}
}

 

[Andrey Kuznetsov]

int count;

public void addUpdate() {
count++;
SwingUtilites.invokeLater(UpdateGui());
}

public void doUpdate() {
if(count > 0) {
count = 0;
UpdateGui();
}
}

sorry, that was wrong...

here is right one:


int count;

public void addUpdate() {
count++;
SwingUtilites.invokeLater(doUpdate());
}

public void doUpdate() {
if(count > 0) {
count = 0;
UpdateGui();
}
}

 

[drcode]

hmm... I like this approach- It's quite a bit simpler than what I was
thinking, but still looks like it will work- Thanks!

 

[Andrey Kuznetsov]

hmm... I like this approach- It's quite a bit simpler than what I was

thinking, but still looks like it will work- Thanks!

yeah, to keep it simple is the most important thing

 

[Chris Uppal]

int count;

public void addUpdate() {
count++;
SwingUtilites.invokeLater(doUpdate());
}

Just to add, in case it's not already obvious:

Since count is being accessed from two threads, you should have some
synchonisation in there too.

-- chris

 

[Andrey Kuznetsov]

int count;

Just to add, in case it's not already obvious:

Since count is being accessed from two threads, you should have some
synchonisation in there too.

in worst case you'll get 2 gui updates instead of 1. Does it really matters?
And if gui update takes longer then it is rather unlikely that you get it
twice!

 

[Chris Uppal]

in worst case you'll get 2 gui updates instead of 1. Does it really
matters?

In the worst case the change made to count by one thread will never be visible
to the other thread at all.

-- chris

 

[Andrey Kuznetsov]

Since count is being accessed from two threads, you should have some

In the worst case the change made to count by one thread will never be
visible
to the other thread at all.

hmm, then make count volatile and don't worry about it.