Faster hashCode using the Effective Java method. (#14)

Caching the hashCode value in the object is a slow-down in my tests.

Author: Tyler

src/main/java/com/javadocmd/simplelatlng/LatLng.java

@@ -185,8 +185,10 @@ public boolean equals(Object obj) {
 
 	@Override
 	public int hashCode() {
-		String s = Long.toString(latitude) + "|" + Long.toString(longitude);
-		return s.hashCode();
+		int result = 1;
+		result = 31 * result + (int) (latitude ^ (latitude >>> 32));
+		result = 31 * result + (int) (longitude ^ (longitude >>> 32));
+		return result;
 	}
 
 	@Override

src/test/java/com/javadocmd/simplelatlng/SpeedProfile.java

@@ -19,14 +19,10 @@
 import java.text.NumberFormat;
 import java.util.Date;
 
-import com.javadocmd.simplelatlng.Geohasher;
-import com.javadocmd.simplelatlng.LatLng;
-import com.javadocmd.simplelatlng.LatLngTool;
 import com.javadocmd.simplelatlng.util.LengthUnit;
 import com.javadocmd.simplelatlng.window.CircularWindow;
 import com.javadocmd.simplelatlng.window.RectangularWindow;
 
-
 /**
  * Basic benchmarking test. Repeats the critical functions
  * a bunch of times and reports how long that took. Also 
@@ -51,6 +47,7 @@ public static void main(String[] args) {
 		p.profileRectangularWindow();
 		p.profileCircularWindow();
 		p.profileGeohasher();
+		p.profileHashCode();
 	}
 
 	private LatLng[] points;
@@ -108,14 +105,19 @@ private void profileGeohasher() {
 
 		System.out.printf("Geohashed and decoded in %s ms.\n", integer.format(end.getTime()
 				- start.getTime()));
+	}
 
-		start = new Date();
-		for (int i = 0; i < points.length; i++) {
-			points[i].hashCode();
+	private void profileHashCode() {
+		// Repeat 5 times in hopes of detecting a caching benefit if any exists.
+		Date start = new Date();
+		for (int j = 0; j < 5; j++) {
+			for (int i = 0; i < points.length; i++) {
+				points[i].hashCode();
+			}
 		}
-		end = new Date();
+		Date end = new Date();
 
-		System.out.printf("hashCode() in %s ms.\n", integer.format(end.getTime()
+		System.out.printf("hashCode() 5x in %s ms.\n", integer.format(end.getTime()
 				- start.getTime()));
 	}