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Calendar Indexing

Indexing of components and properties provides a mechanism to improve the performance of component and property retrieval from calendar data. Typically you might use indexing in situations where you are repeatedly inspecting a calendar for components with specific property values and/or properties with specific parameter values.

Example

An example scenario might be where you have regular updates to input calendar data and need to identify if events in that calendar already exist in a master calendar. As you would be repeatedly inspecting the master calendar for events, it would make sense to index the components in this calendar as follows:

IndexedComponentList indexedEvents = new IndexedComponentList(myCalendar.getComponents(Component.VEVENT), Property.UID);

Note that we are using the UID property to identify unique events. Now we can use the indexed list to quickly identify if an event exists already as follows:

for (Iterator i = inputCalendar.getComponents(Component.VEVENT).iterator(); i.hasNext();) {
  VEvent event = (VEvent) i.next();
  if (indexedEvents.getComponent(event.getUid().getValue()) == null) {
    myCalendar.getComponents().add(event);
  }
}

We should also incorporate checking for modified events as well, which can be achieved by simply comparing two events for equality as follows:

for (Iterator i = inputCalendar.getComponents(Component.VEVENT).iterator(); i.hasNext();) {
  VEvent event = (VEvent) i.next();

  Component existing = indexedEvents.getComponent(event.getUid().getValue());
  if (existing == null) {
    myCalendar.getComponents().add(event);
  }
  else if (!event.equals(existing)) {
    // remove existing event and add modified one..
    myCalendar.getComponents().remove(existing);
    myCalendar.getComponents().add(event);
  }
}

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