001 package ps2;
002
003
004 /**
005 * <p>
006 * A GeoPoint models a point on the earth. GeoPoints are immutable.
007 * </p>
008 *
009 * <p>
010 * North latitudes and east longitudes are represented by positive
011 * numbers. South latitudes and west longitudes are represented by
012 * negative numbers.
013 * </p>
014 *
015 * <p>
016 * The code may assume that the represented points are nearby Seattle.
017 * </p>
018 *
019 * <p>
020 * <b>Implementation hint</b>:<br /> Seattle is at approximately 47
021 * deg. 36 min. 35 sec. N latitude and 122 deg. 19 min. 59 sec. W
022 * longitude. There are 60 minutes per degree, and 60 seconds per
023 * minute. So, in decimal, these correspond to 47.609722 North
024 * latitude and -122.333056 East longitude. The constructor takes
025 * integers in millionths of degrees. To create a new GeoPoint
026 * located in Seattle, use: <tt>GeoPoint seattle = new
027 * GeoPoint(47609722, -122333056);</tt>
028 * </p>
029 *
030 * <p>
031 * Near Seattle, there are approximately 69.04 miles per degree of
032 * latitude and 47.574 miles per degree of longitude. An
033 * implementation should use these values when determining distances
034 * and headings.
035 * </p>
036 *
037 * @specfield latitude : real // measured in degrees latitude
038 * @specfield longitude : real // measured in degrees longitude
039 **/
040 public class GeoPoint {
041
042 /** Minimum value the latitude field can have in this class. **/
043 public static final int MIN_LATITUDE = -90 * 1000000;
044
045 /** Maximum value the latitude field can have in this class. **/
046 public static final int MAX_LATITUDE = 90 * 1000000;
047
048 /** Minimum value the longitude field can have in this class. **/
049 public static final int MIN_LONGITUDE = -180 * 1000000;
050
051 /** Maximum value the longitude field can have in this class. **/
052 public static final int MAX_LONGITUDE = 180 * 1000000;
053
054
055 /**
056 * Approximation used to determine distances and headings using a
057 * "flat earth" simplification.
058 **/
059 public static final double MILES_PER_DEGREE_LATITUDE = 69.04;
060
061 /**
062 * Approximation used to determine distances and headings using a
063 * "flat earth" simplification.
064 **/
065 public static final double MILES_PER_DEGREE_LONGITUDE = 46.574;
066
067
068 // FIELDS
069
070
071 // Constructors
072
073 /**
074 * @requires the (latitude, longitude) point expressed in
075 * millionths of a degree is valid, such that
076 * MIN_LATITUDE <= latitude <= MAX_LATITUDE and
077 * MIN_LONGITUDE <= longitude <= MAX_LONGITUDE
078 *
079 * @effects constructs a GeoPoint from a latitude and
080 * longitude given in millionths of degrees.
081 **/
082 public GeoPoint(int latitude, int longitude) {
083 throw new RuntimeException("Not yet implemented");
084 }
085
086
087 /**
088 * Checks that the representation invariant holds (if any).
089 **/
090 // Throws a RuntimeException if the rep invariant is violated.
091 private void checkRep() throws RuntimeException {
092 throw new RuntimeException("Not yet implemented");
093 }
094
095
096 // Observers
097
098 /**
099 * the latitude of the GeoPoint object, in millionths of degrees.
100 **/
101 public int getLatitude() {
102 throw new RuntimeException("Not yet implemented");
103 }
104
105
106 /**
107 * the longitude of the GeoPoint object, in millionths of degrees.
108 **/
109 public int getLongitude() {
110 throw new RuntimeException("Not yet implemented");
111 }
112
113
114 /**
115 * Computes the distance between GeoPoints.
116 * @requires gp != null
117 * @return The distance, in miles, from this to gp, using the
118 * flat-surface, near Seattle approximation.
119 **/
120 public double distanceTo(GeoPoint gp) {
121 throw new RuntimeException("Not yet implemented");
122 }
123
124
125 /**
126 * Computes the compass heading between GeoPoints.
127 * @requires gp != null && !this.equals(gp)
128 * @return The compass heading h from this to
129 * gp, in degrees, using the flat-surface, near Seattle
130 * approximation, such that 0 <= h < 360. In compass
131 * headings, north = 0, east = 90, south = 180, and west = 270.
132 **/
133 public double headingTo(GeoPoint gp) {
134 throw new RuntimeException("Not yet implemented");
135 }
136
137
138 /**
139 * Compares the specified Object with this GeoPoint for equality.
140 * @return gp != null && (gp instanceof GeoPoint)
141 * && gp.latitude = this.latitude && gp.longitude = this.longitude
142 **/
143 public boolean equals(Object gp) {
144 throw new RuntimeException("Not yet implemented");
145 }
146
147
148 /**
149 * @return a valid hashcode for this GeoPoint.
150 **/
151 public int hashCode() {
152 // This implementation will work, but you may want to modify
153 // it later for improved performance. If you do change the
154 // implementation, make sure it satisfies the hashCode
155 // invariant. That is, if equals returns true for two
156 // objects, then they must have the same hashCode.
157 return (1);
158 }
159
160
161 /**
162 * @return a string representation of this GeoPoint.
163 **/
164 public String toString() {
165 throw new RuntimeException("Not yet implemented");
166 }
167
168 } // GeoPoint