Calendar Toolbox

Introduction

Calendar Toolbox is a Java library designed to simplify the creation of .ics files, adhering to the iCalendar specification (RFC 5545). This library provides developers with a straightforward API to generate calendar events that can be imported into popular calendar applications such as Microsoft Outlook, Google Calendar, and Apple Calendar.

With Calendar Toolbox, you can effortlessly create, customise, and export calendar event files programmatically, enabling integration of calendar functionalities into your Java applications with minimal effort.

Features

Full RFC 5545 Compliance — Supports standard iCalendar components including VEVENT, VTODO, VJOURNAL, VFREEBUSY, VTIMEZONE, and VALARM.
Fluent Builder Pattern — All components and properties use builder pattern for readable and intuitive construction.
Type-Safe Properties — Strongly typed properties and parameters ensure correctness at compile time.
Custom Extensions — Support for custom X- properties at both calendar and component level.
Lightweight — Zero external dependencies for core functionality.

Installation

Gradle with Kotlin DSL

Maven

build.gradle.kts

dependencies {
  implementation("com.onixbyte:calendar-toolbox:1.1.0")
}

Quick Start

import com.onixbyte.calendar.Calendar;
import com.onixbyte.calendar.component.Event;
import com.onixbyte.calendar.component.property.*;
import com.onixbyte.calendar.property.*;

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;

public class CalendarExample {

    public static void main(String[] args) {
        // Create required date-time properties
        var now = ZonedDateTime.now(ZoneOffset.UTC);
        var dtstamp = DateTimeStamp.of(now);
        var uid = UniqueIdentifier.of("meeting-001@example.com");
        var dtstart = DateTimeStart.of(
            LocalDateTime.of(2025, 8, 15, 9, 0),
            "America/New_York"
        );
        var dtend = DateTimeEnd.of(
            LocalDateTime.of(2025, 8, 15, 10, 0),
            "America/New_York"
        );
        var summary = Summary.of("Team Standup");
        var description = Description.of("Daily team standup meeting.");

        // Build the event
        var event = Event.builder()
            .withDateTimeStamp(dtstamp)
            .withUniqueIdentifier(uid)
            .withDateTimeStart(dtstart)
            .withDateTimeEnd(dtend)
            .withSummary(summary)
            .withDescription(description)
            .build();

        // Build the calendar and output .ics content
        var calendar = Calendar.builder()
            .withCalendarScale(CalendarScale.of("GREGORIAN"))
            .withMethod(Method.of("PUBLISH"))
            .withProductIdentifier(ProductIdentifier.of("-//OnixByte//Calendar Toolbox//EN"))
            .withVersion(Version.of("2.0"))
            .withComponents(event)
            .build();

        System.out.println(calendar.formatted());
    }
}

This produces an .ics string that can be saved to a file or sent via email.

License

Calendar Toolbox is open-source software released under the MIT License.

Calendar Toolbox#

#Introduction

#Features

#Installation