/**
* Retrieves an entity of the given type from the graph randomly.
*
* @param <E>
* @param entityType
* @return The randomly selected entity from the graph.
*/
protected final <E extends IEntity> E getRandomEntity(Class<E> entityType) {
final Set<E> set = graph.getEntitiesByType(entityType);
if (set == null || set.size() == 0) {
throw new IllegalStateException("No entities of the given type yet exist.");
} else if (set.size() == 1) {
return set.iterator().next();
}
return getNthEntity(entityType, randomInt(set.size()) + 1);
}
/**
* Attempts to retrive the Nth (1-based) entity of the given type.
*
* @param <E>
* @param entityType
* @param name the entity name (entity type must be implement {@link INamedEntity}).
* @return the matching entity or <code>null</code> if not found
* @throws IllegalArgumentException When the given entity type does not implement {@link
* INamedEntity}
*/
protected final <E extends IEntity> E getEntityByName(Class<E> entityType, String name)
throws IllegalArgumentException {
if (!INamedEntity.class.isAssignableFrom(entityType)) {
throw new IllegalArgumentException(
"Entity type: " + entityType + " is not a named entity type");
}
final Set<E> set = graph.getEntitiesByType(entityType);
if (set != null) {
for (final E e : set) {
final String ename = ((INamedEntity) e).getName();
if (ename != null && ename.equals(name)) return e;
}
}
// not found
return null;
}
/**
* Attempts to retrive the Nth (1-based) entity of the given type.
*
* @param <E>
* @param entityType
* @param n 1-based
* @return the Nth entity or <code>null</code> if n is greater than the number of entities of the
* given type.
*/
protected final <E extends IEntity> E getNthEntity(Class<E> entityType, int n) {
final Set<E> set = graph.getEntitiesByType(entityType);
final int size = set == null ? 0 : set.size();
if (set != null && size >= n) {
int i = 0;
for (final E e : set) {
if (++i == n) {
return e;
}
}
}
throw new IllegalStateException(
size
+ " entities exist of type "
+ entityType
+ " exist but number "
+ n
+ " was requested.");
}