org.jowidgets.util.collection

Interface IObserverSet<OBSERVER_TYPE>

Type Parameters:

OBSERVER_TYPE - The type of the observer hold by this set

All Superinterfaces:

java.lang.Iterable<OBSERVER_TYPE>

public interface IObserverSet<OBSERVER_TYPE>
extends java.lang.Iterable<OBSERVER_TYPE>

A set designed to hold observers when implementing the observer pattern For this use case, the set has the following contract 1. Observers exists only once (its a set), adding them a second time will not modify the set This will be done to avoid that listeners will be fired more than once in the case they was added accidently more than once. This also ensures, that after invoking the remove() method the listener no longer remains in the set because it was added more than once before accidently. This protects from heavy to find bugs where listeners was not removed correctly. 2. Iteration over the set is done in the same order the elements was added It's reasonable to iterate always in the same order to avoid indeterministic behavior, e.g. to reproduce bugs. 3. Iteration is always done with a defensive copy, so changing the set while iterating over it is explicitly allowed, but the iterator itself is unmodifiable. So changing the set while iterating over it must be done with add() and remove() The are many cases where it is very practical the remove a listener while it will be invoked, e.g. on dispose or for binding issues Implementations have not to be threadsafe. Implementors can assume that all modifications will be done in the same thread and have not have to check the thread explicitly.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(OBSERVER_TYPE observer) Adds an observer to the set.
void	clear() Removes all elements from the set an releases the used memory
boolean	remove(OBSERVER_TYPE observer) Removes an observer from the set.

Methods inherited from interface java.lang.Iterable

iterator

Method Detail

add

void add(OBSERVER_TYPE observer)

Adds an observer to the set. If the observer was added already, the set remains unchanged

Parameters:

observer - The observer to add, not null

Throws:

java.lang.IllegalArgumentException - if the observer is null

remove

boolean remove(OBSERVER_TYPE observer)

Removes an observer from the set. If the observer is not a element of the set, the set remains unchanged

Parameters:

observer - The observer to remove, not null

Returns:

true if the set container the given element (and so it was removed)

Throws:

java.lang.IllegalArgumentException - if the given observer is null

clear

void clear()

Removes all elements from the set an releases the used memory