001 package ps2;
002
003 /**
004 * <p>
005 * A GeoSegment models a straight line segment on the earth.
006 * GeoSegments are immutable.
007 * </p>
008 *
009 * <p>
010 * A compass heading is a nonnegative real number less than 360. In
011 * compass headings, north = 0, east = 90, south = 180, and west =
012 * 270.
013 * </p>
014 *
015 * <p>
016 * When used in a map, a GeoSegment might represent part of a street,
017 * boundary, or other feature.
018 * As an example usage, this map
019 * <pre>
020 * Penny Lane a
021 * |
022 * i--j--k Abbey Road
023 * |
024 * z
025 * </pre>
026 * could be represented by the following GeoSegments:
027 * ("Penny Lane", a, i), ("Penny Lane", z, i),
028 * ("Abbey Road", i, j), and ("Abbey Road", j, k).
029 * </p>
030 *
031 * <p>
032 * A name is given to all GeoSegment objects so that it is possible to
033 * differentiate between two GeoSegment objects with identical
034 * GeoPoint endpoints. Equality between GeoSegment objects requires
035 * that the names be equal String objects and the respective start and end
036 * points be equal GeoPoint objects.
037 * </p>
038 *
039 * @specfield name : String // name of the geographic feature identified
040 * @specfield p1 : GeoPoint // first endpoint of the segment
041 * @specfield p2 : GeoPoint // second endpoint of the segment
042 * @derivedfield length : real // straight-line distance between p1 and p2, in miles
043 * @derivedfield heading : angle // compass heading from p1 to p2, in degrees
044 **/
045 public class GeoSegment {
046
047 // FIELDS
048
049 // Constructors
050
051 /**
052 * @requires name != null && p1 != null && p2 != null
053 * @effects constructs a new GeoSegment with the specified
054 * name and endpoints
055 **/
056 public GeoSegment(String name, GeoPoint p1, GeoPoint p2) {
057 throw new RuntimeException("Not yet implemented");
058 }
059
060
061 /**
062 * Checks that the representation invariant holds (if any).
063 **/
064 // Throws a RuntimeException if the rep invariant is violated.
065 private void checkRep() throws RuntimeException {
066 throw new RuntimeException("Not yet implemented");
067 }
068
069
070 // Producers
071
072 /**
073 * Returns a new GeoSegment like this one, but with its endpoints
074 * reversed.
075 * @return a new GeoSegment gs such that
076 * gs.name = this.name
077 * && gs.p1 = this.p2
078 * && gs.p2 = this.p1
079 **/
080 public GeoSegment reverse() {
081 throw new RuntimeException("Not yet implemented");
082 }
083
084
085 // Observers
086
087 /**
088 * @return the name of this GeoSegment.
089 **/
090 public String getName() {
091 throw new RuntimeException("Not yet implemented");
092 }
093
094
095 /**
096 * @return first endpoint of the segment.
097 **/
098 public GeoPoint getP1() {
099 throw new RuntimeException("Not yet implemented");
100 }
101
102
103 /**
104 * @return second endpoint of the segment.
105 **/
106 public GeoPoint getP2() {
107 throw new RuntimeException("Not yet implemented");
108 }
109
110
111 /**
112 * @return the length of the segment, using the flat-surface,
113 * near-Seattle approximation.
114 **/
115 public double getLength() {
116 throw new RuntimeException("Not yet implemented");
117 }
118
119
120 /**
121 * @requires this.length != 0
122 * @return the compass heading from p1 to p2, in degrees, using
123 * the flat-surface, near-Seattle approximation.
124 **/
125 public double getHeading() {
126 throw new RuntimeException("Not yet implemented");
127 }
128
129
130 /**
131 * Compares the specified Object with this GeoSegment for
132 * equality.
133 * @return gs != null && (gs.getClass() == GeoSegment.class)
134 * && gs.name = this.name && gs.p1 = this.p1 && gs.p2 = this.p2
135 **/
136 public boolean equals(Object gs) {
137 throw new RuntimeException("Not yet implemented");
138 }
139
140
141 /**
142 * @return a valid hashcode for this.
143 **/
144 public int hashCode() {
145 // This implementation will work, but you should modify
146 // it later for improved performance. If you do change the
147 // implementation, make sure it satisfies the hashCode
148 // invariant. That is, if equals returns true for two
149 // objects, then they must have the same hashCode.
150 return (1);
151 }
152
153
154 /**
155 * @return a string representation of this.
156 **/
157 public String toString() {
158 throw new RuntimeException("Not yet implemented");
159 }
160
161 } // GeoSegment