001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
055
056
057
058
059
060
061
062
063
064
065
066
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
091
092
093
094
095
096
097
098
099
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
// Exercise 1.2.19 (Solution published at http://algs4.cs.princeton.edu/)
package algs12;
import java.util.Arrays;
import java.util.Comparator;
import stdlib.*;
/* ***********************************************************************
 *  Compilation:  javac Date.java
 *  Execution:    java Date
 *
 *  An immutable data type for dates.
 *
 *************************************************************************/

public class Date implements Comparable<Date> {
  private static final int[] DAYS = { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

  private final int month;   // month (between 1 and 12)
  private final int day;     // day   (between 1 and DAYS[month]
  private final int year;    // year

  // do bounds-checking to ensure object represents a valid date
  public Date(int month, int day, int year) {
    if (!isValid(month, day, year)) throw new Error("Invalid date");
    this.month = month;
    this.day   = day;
    this.year  = year;
  }

  // create new data by parsing from string of the form mm/dd/yy
  public Date(String date) {
    String[] fields = date.split("/");
    if (fields.length != 3) {
      throw new Error("Date parse error");
    }
    month = Integer.parseInt(fields[0]);
    day   = Integer.parseInt(fields[1]);
    year  = Integer.parseInt(fields[2]);
    if (!isValid(month, day, year)) throw new Error("Invalid date");
  }

  public int month() { return month; }
  public int day()   { return day;   }
  public int year()  { return year;  }


  // is the given date valid?
  private static boolean isValid(int m, int d, int y) {
    if (m < 1 || m > 12)      return false;
    if (d < 1 || d > DAYS[m]) return false;
    if (m == 2 && d == 29 && !isLeapYear(y)) return false;
    return true;
  }

  // is y a leap year?
  private static boolean isLeapYear(int y) {
    if (y % 400 == 0) return true;
    if (y % 100 == 0) return false;
    return y % 4 == 0;
  }

  // return the next Date
  public Date next() {
    if (isValid(month, day + 1, year))    return new Date(month, day + 1, year);
    else if (isValid(month + 1, 1, year)) return new Date(month + 1, 1, year);
    else                                  return new Date(1, 1, year + 1);
  }


  // is this Date after b?
  public boolean isAfter(Date b) {
    return compareTo(b) > 0;
  }

  // is this Date a before b?
  public boolean isBefore(Date b) {
    return compareTo(b) < 0;
  }

  // compare this Date to that one
  public int compareTo(Date that) {
    if (this.year  < that.year)  return -1;
    if (this.year  > that.year)  return +1;
    if (this.month < that.month) return -1;
    if (this.month > that.month) return +1;
    if (this.day   < that.day)   return -1;
    if (this.day   > that.day)   return +1;
    return 0;
  }

  // return a string representation of this date
  public String toString() {
    return month + "/" + day + "/" + year;
  }

  // is this Date equal to x?
  public boolean equals(Object x) {
    if (x == this) return true;
    if (x == null) return false;
    if (x.getClass() != this.getClass()) return false;
    Date that = (Date) x;
    return (this.month == that.month) && (this.day == that.day) && (this.year == that.year);
  }

  public int hashCode() {
    int hash = 17;
    hash = 31*hash + Integer.hashCode (month);
    hash = 31*hash + Integer.hashCode (day);
    hash = 31*hash + Integer.hashCode (year);
    return hash;
  }



  // A stupid class!
  private static class MyComp implements Comparator<Date>{
    public int compare (Date o1, Date o2) {
      return o2.compareTo (o1);
    }   
  }
  
  // sample client for testing
  public static void main(String[] args) {
    // using the stupid class:
    Comparator<Date> c1 = new MyComp ();

    // using an inner class:
    Comparator<Date> c2 = new Comparator<Date>() {
      public int compare (Date o1, Date o2) {
        return o2.compareTo (o1);
      }
    };
    
    // using a lambda expression:
    Comparator<Date> c3 = (o1, o2) -> o2.compareTo (o1);  
    
    Date[] dates = new Date[] { new Date(2, 25, 2004), new Date(2, 25, 2003), } ;
    StdOut.println (Arrays.binarySearch (dates, new Date(2, 25, 2003), c1));
    
//    Date today = new Date(2, 25, 2004);
//    StdOut.println(today);
//    for (int i = 0; i < 10; i++) {
//      today = today.next();
//      StdOut.println(today);
//    }
//
//    StdOut.println(today.isAfter(today.next()));
//    StdOut.println(today.isAfter(today));
//    StdOut.println(today.next().isAfter(today));
//
//
//    Date birthday = new Date(10, 16, 1971);
//    StdOut.println(birthday);
//    for (int i = 0; i < 10; i++) {
//      birthday = birthday.next();
//      StdOut.println(birthday);
//    }
  }

}