/**
* Get a provider based on the position in the stack (starting at 0 and ending at size-1).
*
* @param position the position to check for the provider
* @return the provider from the position OR null if there is no provider at that position
*/
public T getProvider(final int position) {
T provider = null;
ProviderHolder<T> holder = getProviderHolder(position);
if (holder != null) {
provider = holder.getProvider();
}
return provider;
}
/**
* Check to make sure all providers are refreshed and any that are no longer valid are flushed out
* of the list.
*
* @return list of valid providers
*/
protected List<T> refresh() {
ArrayList<T> l = new ArrayList<T>();
for (Iterator<ProviderHolder<T>> iterator = providers.iterator(); iterator.hasNext(); ) {
ProviderHolder<T> holder = iterator.next();
T provider = holder.getProvider();
if (provider == null) {
iterator.remove();
} else {
l.add(provider);
}
}
return l;
}
/**
* Remove a provider by the object equality.
*
* @param provider the provider to remove from the stack
* @return true if the provider was found and removed OR false if not found
*/
public boolean removeProvider(T provider) {
if (provider == null) {
throw new IllegalArgumentException("provider to remove cannot be null");
}
boolean removed = false;
refresh();
for (Iterator<ProviderHolder<T>> iterator = providers.iterator(); iterator.hasNext(); ) {
ProviderHolder<T> holder = iterator.next();
T p = holder.getProvider();
if (p == null) {
iterator.remove();
} else {
if (p.equals(provider)) {
iterator.remove();
removed = true;
}
}
}
return removed;
}
