GWT - run command exactly once per event loop - gwt

Question

I'm writing some wrapper classes around zurb foundation.
Foundation widgets need an init() function to be called after the elements have been added to the DOM.
I can accomplish this easily enough with this method:
public static void initWidgets() {
Scheduler.get().scheduleDeferred(new Scheduler.ScheduledCommand() {
#Override
public void execute() {
foundationInit();
}
});
}
...where foundationInit() is a JSNI call to the foundation init() function. I then add a call to initWidgets() in the constructor of any foundation element. So far so good.
However, if multiple foundation widgets are added to the DOM during a particular event loop, then the init() method will be called multiple times. Foundation doesn't actually care about this, but it would be nice to find a way around this.
Is there any scheduler functionality / pattern that'd allow me to schedule a particular command to run only once, no matter how many times the schedule method is called with that command?
Something like: scheduleDeferredIfNotAlreadyScheduled(Command c)
I don't know how to get a handle on the event loop, so I don't know how to reset a flag that'd tell me whether or not to add the command or not.

Answer 1

I don't know any Scheduller command to do that, but it could be done with a static boolean variable, e.g.:
private static boolean initialized;
public static void initWidgets() {
initialized = false;
Scheduler.get().scheduleDeferred(new Scheduler.ScheduledCommand() {
#Override
public void execute() {
if (!initialized) {
initialized = true;
foundationInit();
}
}
});
}

Answer 2

In such case I usually use Guava's Supplier.double checked locking is really safe.
public static Supplier<Boolean> supplier=Suppliers.memoize(new Supplier<Boolean>() {
#Override
public Boolean get() {
foundationInit();
return true;
}
});
public static void initWidgets() {
Scheduler.get().scheduleDeferred(new Scheduler.ScheduledCommand() {
#Override
public void execute() {
boolean initialized=supplier.get();
}
});
}