Instructions

We learned from lecture slides how to read a UML $($Unified Modeling Language$)$ diagram. Here we use one to tell us what class name, member fields, and member methods to code.

$-------------------------------------------------$

GeoLocation

$-------------------------------------------------$

$-$ EARTH$\_$RADIUS$\_$MILES$`$ : double $=3963\mathrm{.}1676$

$-$ latitude : double

$-$ longitude : double

$-------------------------------------------------$

$+$ GeoLocation$()$

$+$ GeoLocation$($lat : double, lon : double$)$

$+$ setLatitude$($lat : double$)$ : void

$+$ getLatitude$()$ : double

$+$ setLongitude$($lon : double$)$ : void

$+$ getLongitude$()$ : double

$+$ distanceFrom$($o : GeoLocation$)$ : double

$-------------------------------------------------$

How to calculate distance of two points on a globe

To measure distance along the surface, we can't just draw a straight line between two points on a spherical shaped object. An explanation is here. We can break down the step for the law of cosines with spheres:

Your distanceFrom$()$ method should:

Convert each object's latitude and longitude value to radians using Math.toRadians$().$

Apply the steps outlined above to find the arcLength $($use the radian lat$/$lon values$).$ Find geometry methods in the Java API Math class.

Return the arcLength times the Earth's radius in miles.

Testing

Writing a program to test your code is a common practice. YOU WILL NOT TURN IN THE TEST PROGRAM!

A simple way to do this is to open another file, called TestGeo $($or whatever$),$ write a main$()$ method that

instantiates a GeoLocation object using the no$-$arg constructor

print getLatitude$()$ and getLongitude$()$ return values $($should be zeros$)$

call the setters

print again to show values were modified to whatever values you passed in

repeat Steps $1-4$ but use the GeoLocation two$-$arg constructor

find the distance between two GeoLocation objects $($estimate the answer to verify your method works$)$