package edu.princeton.cs.algs4.ch12;
import edu.princeton.cs.introcs.*;
/*************************************************************************
* Compilation: javac Date.java
* Execution: java Date
*
* An immutable data type for dates.
*
*************************************************************************/
/**
* The <tt>Date</tt> class is an immutable data type to encapsulate a
* date (day, month, and year).
* <p>
* For additional documentation, see <a href="/algs4/12oop">Section 1.2</a> of
* <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
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
/**
* Initializes a new date from the month, day, and year.
* @param month the month (between 1 and 12)
* @param day the day (between 1 and 28-31, depending on the month)
* @param year the year
* @throws IllegalArgumentException if the date is invalid
*/
public Date(int month, int day, int year) {
if (!isValid(month, day, year)) throw new IllegalArgumentException("Invalid date");
this.month = month;
this.day = day;
this.year = year;
}
/**
* Initializes new date specified as a string in form MM/DD/YYYY.
* @param date the string representation of the date
* @throws IllegalArgumentException if the date is invalid
*/
public Date(String date) {
String[] fields = date.split("/");
if (fields.length != 3) {
throw new IllegalArgumentException("Invalid date");
}
month = Integer.parseInt(fields[0]);
day = Integer.parseInt(fields[1]);
year = Integer.parseInt(fields[2]);
if (!isValid(month, day, year)) throw new IllegalArgumentException("Invalid date");
}
/**
* Return the month.
* @return the month (an integer between 1 and 12)
*/
public int month() {
return month;
}
/**
* Return the day.
* @return the day (an integer between 1 and 31)
*/
public int day() {
return day;
}
/**
* Return the year.
* @return the year
*/
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 year y a leap year?
* @return true if y is a leap year; false otherwise
*/
private static boolean isLeapYear(int y) {
if (y % 400 == 0) return true;
if (y % 100 == 0) return false;
return y % 4 == 0;
}
/**
* Returns the next date in the calendar.
* @return a date that represents the next day after this day
*/
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?
* @return true if this date is after date b; false otherwise
*/
public boolean isAfter(Date b) {
return compareTo(b) > 0;
}
/**
* Is this date before b?
* @return true if this date is before date b; false otherwise
*/
public boolean isBefore(Date b) {
return compareTo(b) < 0;
}
/**
* Compare this date to that date.
* @return { a negative integer, zero, or a positive integer }, depending
* on whether this date is { before, equal to, after } that date
*/
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.
* @return the string representation in the foramt MM/DD/YYYY
*/
public String toString() {
return month + "/" + day + "/" + year;
}
/**
* Is this date equal to x?
* @return true if this date equals x; false otherwise
*/
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);
}
/**
* Return a hash code.
* @return a hash code for this date
*/
public int hashCode() {
int hash = 17;
hash = 31*hash + month;
hash = 31*hash + day;
hash = 31*hash + year;
return hash;
}
/**
* Unit tests the date data type.
*/
public static void main(String[] args) {
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);
}
}
}
/*************************************************************************
* Copyright 2002-2012, Robert Sedgewick and Kevin Wayne.
*
* This file is part of algs4-package.jar, which accompanies the textbook
*
* Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,
* Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.
* http://algs4.cs.princeton.edu
*
*
* algs4-package.jar is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* algs4-package.jar is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with algs4-package.jar. If not, see http://www.gnu.org/licenses.
*************************************************************************/