FAQ: Where is the Zmanim API Main Method?

KosherJava Zmanim API FAQ

Question:

Where is the main method?

Answer:

This is a more technical variant of the “How do I install the Zmanim API Program?”, but coming from someone who already knows that it is a Java program that can’t be installed, but assumes that it can be run. The main method is the entry point to a Java program. Since this is a library/API and not a program, it does not have a main method. The code to generate zmanim is spelled out in the How to Use the Zmanim API page. Below is a full example of a very simple zmanim program that outputs sunrise, sof zman krias shema and sunset for the current day in Lakewood, NJ. Please ensure that the Zmanim jar (download) is in your classpath.

/**
 * This program is a simple demonstration of the kosherjava.com Zmanim API.
 * To compile, ensure that the Zmanim Jar is in your classpath.
 */
import net.sourceforge.zmanim.*;
import net.sourceforge.zmanim.util.*;
import java.util.TimeZone;
public class SimpleZmanim{
	public static void main(String [] args) {
		String locationName = "Lakewood, NJ";
		double latitude = 40.096; //latitude of Lakewood, NJ
		double longitude = -74.222; //longitude of Lakewood, NJ
		double elevation = 0; //optional elevation
		//use a Valid Olson Database timezone listed in java.util.TimeZone.getAvailableIDs()
		TimeZone timeZone = TimeZone.getTimeZone("America/New_York");
		//create the location object
		GeoLocation location = new GeoLocation(locationName, latitude, longitude, elevation, timeZone);
		//create the ZmanimCalendar
		ZmanimCalendar zc = new ZmanimCalendar(location);
		//optionally set the internal calendar. If not set it will default to the current date
		//zc.getCalendar().set(1969, Calendar.FEBRUARY, 8);
		System.out.println("Today's Zmanim for " + locationName);
		System.out.println("Sunrise: " + zc.getSunrise()); //output sunrise
		System.out.println("Sof Zman Shema GRA: " + zc.getSofZmanShmaGRA()); //output Sof Zman Shema GRA
		System.out.println("Sunset: " + zc.getSunset()); //output sunset
	}
}

The following would compile and execute this code (sample from a DOS prompt in Windows).

C:\path\to\code>javac SimpleZmanim.java

C:\path\to\code>java SimpleZmanim

Today's Zmanim for Lakewood, NJ
Sunrise: Thu Nov 05 06:30:27 EST 2009
Sof Zman Shema GRA: Thu Nov 05 09:05:21 EST 2009
Sunset: Thu Nov 05 16:50:02 EST 2009

Please see the Zmanim API documentation for a more complete view of the API.

FAQ: How do I install the Zmanim API Program?

KosherJava Zmanim API FAQ

Question:

How do I install the Zmanim API Program?

Answer:

The Zmanim API is not a program that can be installed, but a Java programming library often referred to as an API (Application Programming Interface). This is a building block to be used by programmers who want to easily include zmanim in their own programs. The Zmanim API allows them to do this with minimal understanding of the way zmanim are calculated. A sample of a program that uses the Zmanim API library is the Zmanim Calendar Generator. The Zmanim Calendar Generator collects user entered location information on the web page and submits this to a small Java program that calculates a year’s worth of zmanim and outputs it as an Excel spreadsheet (using the Apache POI library). A future FAQ may provide a list of current programs that use the Zmanim API.

Plans for a Zmanim API FAQ

KosherJava Zmanim API FAQ
Questions communicated to me via the contact page far exceed the number of comments in the blog. In the hope of clarifying the most common questions related to the Zmanim API and to a lesser degree other parts of this site, I plan on a series of FAQ posts that will hopefully cut down on the number of questions. The list of FAQs may eventually be consolidated into a FAQ page.