Features

This page shows a summary of the most important features of the FullCalendar library, that this addon provides. It is not a full list of all features. If you find any library features missing, please create a feature request.

FullCalendar features

• Adding, updating, and removing calendar entries using a data provider pattern
• Switching between displayed intervals (next month, previous month, etc.)
• Navigating to a specific date or today
• Switching the calendar view (month, basic day/week, agenda day/week, list views, multi-month)
• Setting a locale for week days, number formatting, and first-day-of-week calculation
• Overriding the first day of the week independently of the locale
• Limiting the maximum number of stacked entries per day (except basic views)
• Activating day/week numbers as navigation links
• Setting business hours with multiple time ranges per week
• Creating recurring events (simple recurrence and RFC 5545 RRule)
• Setting a client-side timezone
• Optional Vaadin/Lumo theme
• Custom native JS event handlers for entries
• Client-side event sources (JSON feeds, Google Calendar, iCalendar)

Entry model

The Entry class supports the following properties:

Property	Method	Description
Title	setTitle(String)	Displayed label on the calendar
Start / End	setStart(LocalDate) / setStart(LocalDateTime) / setStart(Instant) and equivalently setEnd(LocalDate) / setEnd(LocalDateTime) / setEnd(Instant)	LocalDate, LocalDateTime, or Instant; LocalDate implies all-day. setEnd is optional — omitting it creates a single-day (or point-in-time) entry
All-day	setAllDay(boolean)	Force all-day rendering regardless of time part
Color	setColor(String)	HTML color string ("#ff3333", "red")
URL	setUrl(String)	FC renders the entry as an <a> tag and navigates on click
Interactive	setInteractive(Boolean)	Per-entry keyboard-focusability; null = inherit global eventInteractive
Editable	setEditable(boolean)	Enable/disable drag and resize for this entry
Display mode	setDisplayMode(DisplayMode)	AUTO, BLOCK, LIST_ITEM, BACKGROUND, INVERSE_BACKGROUND, NONE
Overlap	setOverlap(Boolean)	Whether this entry may overlap others; null = inherit global setting
Constraint	setConstraint(String)	Group id or "businessHours" restricting when this entry may be placed
Recurring (simple)	setRecurringDaysOfWeek / setRecurringStartTime / setRecurringEndTime	Built-in day-of-week recurrence
Recurring duration	setRecurringDuration(String)	ISO 8601 duration for multi-day recurring all-day events (e.g. "P2D")
RRule	setRRule(RRule)	RFC 5545 recurrence rule for complex patterns
Exclusion dates	rrule.excludeDates(LocalDate...)	Dates excluded from an RRule recurrence — set on the RRule builder instance, transferred automatically to the entry
Exclusion rules	rrule.excludeRules(RRule...)	Sub-RRules that exclude patterns of dates (EXRULE). Must be structured RRules built via the fluent API; passing RRule.ofRaw(...) throws IllegalArgumentException. Broken in 7.2.0 / 6.5.0; use 7.2.1 / 6.5.1 or later.
Custom properties	setCustomProperty(String, Object)	Arbitrary data accessible in JS callbacks

RRule — rich recurrence patterns

RRule provides a fluent Java API for RFC 5545 recurrence rules, backed by the @fullcalendar/rrule plugin (bundled automatically).

// Weekly on Monday, Wednesday, Friday
Entry standup = new Entry();
standup.setTitle("Weekly Standup");
standup.setRRule(RRule.weekly()
    .byWeekday(DayOfWeek.MONDAY, DayOfWeek.WEDNESDAY, DayOfWeek.FRIDAY)
    .dtstart(LocalDate.of(2025, 1, 1))
    .until(LocalDate.of(2025, 12, 31)));

// Last Friday of each month
// byWeekday accepts RFC 5545 BYDAY strings: "-1fr" = last Friday, "1mo" = first Monday,
// "-2tu" = second-to-last Tuesday. Positive/negative numbers select the nth occurrence from
// the start/end of the period.
Entry endOfMonth = new Entry();
endOfMonth.setTitle("Monthly Review");
endOfMonth.setRRule(RRule.monthly().byWeekday("-1fr"));

// Raw RFC 5545 string (for patterns not supported by the fluent builder)
Entry custom = new Entry();
custom.setRRule(RRule.ofRaw("FREQ=WEEKLY;BYDAY=MO,WE;INTERVAL=2"));

When to use RRule vs. built-in recurrence:

• Use the built-in recurringDaysOfWeek / recurringStartTime / recurringEndTime for simple weekly patterns — less setup, no plugin required.
• Use RRule for richer patterns: bi-weekly, monthly-by-weekday, yearly, exclusion dates, limited counts, etc.
• The two mechanisms are mutually exclusive per entry: setting an RRule overrides built-in recurrence fields.

DTSTART and the entry's start (7.2.1+ / 6.5.1+): if the RRule has no explicit dtstart(...), the addon uses the entry's start as the recurrence anchor — date-only for all-day entries, local datetime otherwise. An explicit RRule#dtstart(...) wins. Without an anchor, rrule-js generates zero occurrences, which is why an explicit dtstart(...) was effectively required in the earlier patch versions.

Entry URL behaviour

When entry.setUrl(url) is set, FullCalendar renders the entry as an <a> tag and navigates to the URL when clicked. The server-side EntryClickedEvent is still fired when the entry is clicked.

Accessibility

Set setOption(Option.ENTRY_INTERACTIVE, true) to make all entries keyboard-focusable (tabindex="0"), enabling keyboard-only users to Tab to entries and activate them with Enter or Space. By default, only entries with a url property are focusable. Enabling this globally is recommended for WCAG 2.1 AA, Success Criterion 2.1.1. For per-entry control, use Entry.setInteractive(Boolean) (pass null to inherit the global setting).

Additional accessibility options (set via setOption):

• Option.NATIVE_TOOLBAR_BUTTON_HINTS — Map<String, String> of aria-label values for toolbar buttons
• Option.NAV_LINK_HINT / Option.MORE_LINK_HINT / Option.NATIVE_TOOLBAR_VIEW_HINT — screen-reader labels for navigation links, "+N more" overflow links, and view-switcher buttons (use $0 as a runtime placeholder for the count or date value, e.g. "$0 more events")
• Option.CLOSE_HINT / Option.TIME_HINT / Option.ENTRY_HINT — labels for popover close buttons, time displays, and entries

Event handling

Server-side events fired by the calendar:

Event	When fired
TimeslotClickedEvent	User clicks an empty time slot
TimeslotsSelectedEvent	User selects a range of time slots
EntryClickedEvent	User clicks an entry (including keyboard activation when Option.ENTRY_INTERACTIVE is true)
EntryDroppedEvent	User drops an entry after dragging (includes new start/end)
EntryResizedEvent	User resizes an entry (includes new start/end)
EntryDragStartEvent	User begins dragging an entry
EntryDragStopEvent	User releases an entry after dragging (fires regardless of whether a valid drop occurred)
EntryResizeStartEvent	User begins resizing an entry
EntryResizeStopEvent	User releases after resizing (fires regardless of whether a valid resize occurred)
EntryMouseEnterEvent / EntryMouseLeaveEvent	Mouse enters/leaves an entry
DatesRenderedEvent	The current view interval is rendered (use to update labels, refresh data, etc.)
MoreLinkClickedEvent	User clicks the "+N more" overflow link
DayNumberClickedEvent / WeekNumberClickedEvent	User clicks a day/week number (when navLinks is enabled)
BrowserTimezoneObtainedEvent	The client's local timezone is detected on first load
EventSourceFailureEvent	A client-side event source (JSON feed, Google Calendar, iCal) failed to load
ExternalEntryDroppedEvent	An entry from a client-side event source is dropped into the calendar
ExternalEntryResizedEvent	An entry from a client-side event source is resized

Event sources (client-side)

In addition to the server-managed EntryProvider, the calendar supports client-side event sources that load data directly in the browser:

// JSON feed — FC fetches from your REST endpoint with start/end query parameters
JsonFeedEventSource jsonFeed = new JsonFeedEventSource("https://example.com/events");
// .withEditable(true)  // optional: enable drag/drop for entries from this source
calendar.addClientSideEventSource(jsonFeed);

// Google Calendar
GoogleCalendarEventSource google = new GoogleCalendarEventSource("calendarId@gmail.com");
google.withApiKey("YOUR_API_KEY");  // or set globally: calendar.setOption(Option.EXTERNAL_EVENT_SOURCE_GOOGLE_CALENDAR_API_KEY, key)
calendar.addClientSideEventSource(google);

// iCalendar (.ics) feed
ICalendarEventSource ical = new ICalendarEventSource("https://example.com/calendar.ics");
calendar.addClientSideEventSource(ical);

Client-side event source entries are read-only by default (editable = false). To enable drag/drop and resize for a source, call .withEditable(true) on the source instance before adding it to the calendar. When a drag-drop occurs, an ExternalEntryDroppedEvent is fired; when a resize occurs, an ExternalEntryResizedEvent is fired (both instead of their server-managed counterparts EntryDroppedEvent / EntryResizedEvent).

View-specific options

Override any option for a specific view type only. The view type string is the FullCalendar view name (e.g. "dayGridMonth", "dayGridWeek", "timeGridWeek", "timeGridDay", "listWeek") or a prefix that matches multiple views (e.g. "timeGrid" matches both timeGridWeek and timeGridDay). You can also pass a CalendarView enum value instead of a raw string.

// Limit event rows to 3 in month view, no limit in other views
calendar.setViewSpecificOption("dayGridMonth", Option.DAY_MAX_EVENT_ROWS, 3);

// Custom slot duration only in time-grid views
// All three forms work thanks to the DurationConverter:
calendar.setViewSpecificOption("timeGrid", Option.SLOT_DURATION, "00:30:00");     // string
calendar.setViewSpecificOption("timeGrid", Option.SLOT_DURATION, Duration.ofMinutes(30));  // Duration
calendar.setViewSpecificOption("timeGrid", Option.SLOT_DURATION, LocalTime.of(0, 30));    // LocalTime

Navigation

calendar.next();           // next interval
calendar.previous();       // previous interval
calendar.today();          // jump to today
calendar.gotoDate(date);   // jump to a specific date

Scheduler features

The scheduler extension integrates the features of the commercial FullCalendar Scheduler plugin. A valid license key is required for production use (see Scheduler license).

• Adding and removing resources (including hierarchical resource trees)
• Linking one or multiple resources to entries (ResourceEntry)
• Resource grouping by field value (setOption(SchedulerOption.RESOURCE_GROUP_FIELD, ...)) with customisable group headers
• Multiple resource area columns with support for static text and interactive Vaadin components (setResourceAreaColumns)
• Timeline views and vertical resource views (SchedulerView)
• Filtering and ordering resources on the server side

Event handling:

• Timeslot clicked / selected
• Entry dropped (including the resource assignment after drop)

Component Resource Area Columns

In addition to static text columns, the resource area sidebar can display interactive Vaadin components (DatePicker, TextField, ComboBox, etc.) — one component instance per resource. This pattern mirrors Vaadin Grid's ComponentColumn and is useful for:

• Inline editing of resource metadata (deadlines, priority, owner, notes)
• One-way binding to entry properties (display entry start/end dates, duration)
• Two-way binding (component change updates entry; entry change updates component)

Components are created by a callback that receives the Resource and returns a component instance. They are fully interactive — users can type, select, open dropdowns, etc. — and survive FullCalendar view changes and re-renders. Type-safe runtime access is provided at any time via getComponent(resource).

// Define a component column with a callback
ComponentResourceAreaColumn<DatePicker> deadlineCol = new ComponentResourceAreaColumn<>(
    "deadline", "Deadline",
    resource -> {
        DatePicker picker = new DatePicker();
        picker.setWidth("130px");
        return picker;
    }
);

// Mix with regular text columns
scheduler.setResourceAreaColumns(
    new ResourceAreaColumn("title", "Name").withWidth("200px"),
    deadlineCol.withWidth("160px")
);

// Update a component at any time (type-safe, no casting)
deadlineCol.getComponent(resource).ifPresent(picker ->
    picker.setValue(LocalDate.now())
);

Developer Tools

• MCP Server: discontinued — see MCP-Server for why and what to use instead.