Issue #2: fix NPE in isDay()/isNight() for extreme latitudes.

cli/pom.xml

@@ -27,7 +27,7 @@
 	<parent>
 		<groupId>ca.rmen</groupId>
 		<artifactId>sunrise-sunset</artifactId>
-		<version>1.0.1</version>
+		<version>1.0.2</version>
 	</parent>
 
 	<artifactId>sunrise-sunset-cli</artifactId>

library/pom.xml

@@ -27,12 +27,12 @@
 	<parent>
 		<groupId>ca.rmen</groupId>
 		<artifactId>sunrise-sunset</artifactId>
-		<version>1.0.1</version>
+		<version>1.0.2</version>
 	</parent>
 
 	<artifactId>lib-sunrise-sunset</artifactId>
 	<packaging>jar</packaging>
-	<version>1.0.1</version>
+	<version>1.0.2</version>
 	<name>lib-sunrise-sunset</name>
 	<url>http://rmen.ca</url>
 

library/src/main/java/ca/rmen/sunrisesunset/SunriseSunset.java

@@ -360,6 +360,24 @@ public static boolean isDay(double latitude, double longitude) {
 	public static boolean isNight(double latitude, double longitude) {
 		Calendar today = Calendar.getInstance();
 		Calendar[] sunriseSunset = getSunriseSunset(today, latitude, longitude);
+		// In extreme latitudes, there may be no sunrise/sunset time in summer or
+		// winter, because it will be day or night 24 hours
+		if (sunriseSunset == null) {
+			int month = today.get(Calendar.MONTH); // Reminder: January = 0
+			if (latitude > 0) {
+				if (month >= 3 && month <= 10) {
+					return false; // Always day at the north pole in June
+				} else {
+					return true; // Always night at the north pole in December
+				}
+			} else {
+				if (month >= 3 && month <= 10) {
+					return true; // Always night at the south pole in June
+				} else {
+					return false; // Always day at the south pole in December
+				}
+			}
+		}
 		Calendar sunrise = sunriseSunset[0];
 		Calendar sunset = sunriseSunset[1];
 		Calendar now = Calendar.getInstance(TimeZone.getTimeZone("UTC"));

library/src/test/java/ca/rmen/sunrisesunset/test/SunriseSunsetTest.java

@@ -228,6 +228,7 @@ public void testAntarctica() {
 		testCivilTwilight("Antarctica/McMurdo", "20151221", -77.8456, 166.6693, null, null);
 		testNauticalTwilight("Antarctica/McMurdo", "20151221", -77.8456, 166.6693, null, null);
 		testAstronomicalTwilight("Antarctica/McMurdo", "20151221", -77.8456, 166.6693, null, null);
+		testDayOrNight("Antarctica", "Antarctica/McMurdo", -77.8456, 166.6693, null, null, null, null);
 	}
 
 	/**
@@ -712,11 +713,18 @@ private void testDayOrNight(String name, String timeZoneString,
 
 		Calendar now = Calendar.getInstance(TimeZone
 				.getTimeZone(timeZoneString));
+		String nowString = format(DATE_FORMAT_MINUTES, now);
+
+		if (earliestSunriseString == null || latestSunriseString == null
+				|| earliestSunsetString == null || latestSunsetString == null) {
+			// For extreme latitudes around June/December, we'll just return here.  The previous lines at least make
+			// sure the library doesn't crash.
+			return;
+		}
 		Calendar earliestSunrise = getCalendarAtTime(now, earliestSunriseString);
 		Calendar latestSunrise = getCalendarAtTime(now, latestSunriseString);
 		Calendar earliestSunset = getCalendarAtTime(now, earliestSunsetString);
 		Calendar latestSunset = getCalendarAtTime(now, latestSunsetString);
-		String nowString = format(DATE_FORMAT_MINUTES, now);
 		if (isDay) {
 			Assert.assertTrue("In " + name + ", " + nowString
 					+ " is before sunrise at " + earliestSunriseString

pom.xml

@@ -27,7 +27,7 @@
 	<groupId>ca.rmen</groupId>
 	<artifactId>sunrise-sunset</artifactId>
 	<packaging>pom</packaging>
-	<version>1.0.1</version>
+	<version>1.0.2</version>
 	<name>sunrise-sunset</name>
 	<url>http://rmen.ca</url>