@Override
public void add(int index, O element) {
if (element == null) {
throw new NullPointerException();
}
if (handler.canAdd(element)) {
delegate.add(index, element);
handler.added(element);
}
}
@Override
public O set(int index, O element) {
if (element == null) {
throw new NullPointerException();
}
O oldValue = delegate.set(index, element);
if (oldValue != element) {
handler.removed(oldValue);
handler.added(element);
}
return oldValue;
}
@Override
public O remove(int index) {
O oldValue = delegate.remove(index);
if (oldValue != null) {
handler.removed(oldValue);
}
return oldValue;
}
