001package algs34;
002import stdlib.*;
003import java.util.HashSet;
004/* ***********************************************************************
005 * Floating point is a pain!
006 *************************************************************************/
007
008public final class XBadPoint {
009        static class BadPoint {
010                private final double x;
011                private final double y;
012                public BadPoint(double x, double y) { this.x = x; this.y = y; }
013                public String toString() { return "(" + x + ", " + y + ")";  }
014
015                public boolean equals(Object other) {
016                        if (other == this) return true;
017                        if (other == null || other.getClass() != this.getClass()) return false;
018                        BadPoint that = (BadPoint) other;
019                        if (this.x != that.x) return false;
020                        if (this.y != that.y) return false;
021                        return true;
022                }
023                public int hashCode() {
024                        int h = 17;
025                        h = 31*h + Double.hashCode(x);
026                        h = 31*h + Double.hashCode(y);
027                        return h;
028                }
029        }
030
031        public static void main(String[] args) {
032                BadPoint a = new BadPoint(0.0, 0.0);
033                BadPoint b = new BadPoint(0.0, 0.0);
034                BadPoint e = new BadPoint(0.0,-0.0);
035                StdOut.format("a = %s [hashcode=%d]\n", a, a.hashCode ());
036                StdOut.format("b = %s [hashcode=%d]\n", b, b.hashCode ());
037                StdOut.format("e = %s [hashcode=%d]\n", e, e.hashCode ());
038
039                HashSet<BadPoint> set = new HashSet<>();
040                set.add(a);
041                StdOut.println("Added a");
042                StdOut.println("a == b:      " + (a == b));
043                StdOut.println("a.equals(b): " + (a.equals(b)));
044                StdOut.println("contains b:  " + set.contains(b));
045                StdOut.println("a == e:      " + (a == e));
046                StdOut.println("a.equals(e): " + (a.equals(e)));
047                StdOut.println("contains e:  " + set.contains(e));
048        }
049}