Computer Science/61b/Homework/hw2/Date.java
< Computer Science | 61b | Homework | hw2
Revision as of 03:51, 20 February 2023 by Lensovet (talk | contribs) (Lensovet moved page CS/61b/Homework/hw2/Date.java to Computer Science/61b/Homework/hw2/Date.java)
- This page contains computer code. Unlike all articles on the lensowiki, which are released under the GFDL, this code is released under the GPL.
Copyright 2006, 2007 Paul Borokhov. All rights reserved.
This code 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 2 of the License, or (at your option) any later version.
The code 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 this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
/* Date.java */
import java.io.*;
class Date {
/* Put your private data fields here. */
private int month;
private int day;
private int year;
/** Constructs a date with the given month, day and year. If the date is
* not valid, the entire program will halt with an error message.
* @param month is a month, numbered in the range 1...12.
* @param day is between 1 and the number of days in the given month.
* @param year is the year in question, with no digits omitted.
*/
public Date(int month, int day, int year) {
if (isValidDate(month, day, year)) {
this.month = month;
this.day = day;
this.year = year;
} else {
System.out.println("You have entered in invalid date");
System.exit(0); }
}
/** Constructs a Date object corresponding to the given string.
* @param s should be a string of the form "month/day/year" where month must
* be one or two digits, day must be one or two digits, and year must be
* between 1 and 4 digits. If s does not match these requirements or is not
* a valid date, the program halts with an error message.
*/
public Date(String s) {
int[] datearray = new int[3];
for (int i=0; i<3; i++)
{ datearray[i] = Integer.parseInt(s.split("/", 3)[i]); }
if (isValidDate(datearray[0], datearray[1], datearray[2])) {
this.month = datearray[0];
this.day = datearray[1];
this.year = datearray[2];
} else {
System.out.println("You have entered in invalid date");
System.exit(0); }
}
/** Checks whether the given year is a leap year.
* @return true if and only if the input year is a leap year.
*/
public static boolean isLeapYear(int year) {
if (year%400 != 0 && year%4 == 0) { return true; }
else { return false; }
}
/** Returns the number of days in a given month.
* @param month is a month, numbered in the range 1...12.
* @param year is the year in question, with no digits omitted.
* @return the number of days in the given month.
*/
public static int daysInMonth(int month, int year) {
if (isLeapYear(year) && month == 2) { return 29; }
switch (month) {
case 1: return 31;
case 2: return 28;
case 3: return 31;
case 4: return 30;
case 5: return 31;
case 6: return 30;
case 7: return 31;
case 8: return 31;
case 9: return 30;
case 10: return 31;
case 11: return 30;
case 12: return 31;
// default: System.out.println("Invalid month");
}
return 0;
}
/** Checks whether the given date is valid.
* @return true if and only if month/day/year constitute a valid date.
*
* Years prior to A.D. 1 are NOT valid.
*/
public static boolean isValidDate(int month, int day, int year) {
if (month>12 || month <1 || day<1 || day>daysInMonth(month, year) || year<1) { return false; }
else { return true; }
}
/** Returns a string representation of this date in the form month/day/year.
* The month, day, and year are printed in full as integers; for example,
* 12/7/2006 or 3/21/407.
* @return a String representation of this date.
*/
public String toString() {
return (this.month + "/" + this.day + "/" + this.year);
}
/** Determines whether this Date is before the Date d.
* @return true if and only if this Date is before d.
*/
public boolean isBefore(Date d) {
if((this.dayInYear() < d.dayInYear() && this.year == d.year) || this.year < d.year) { return true; }
// if (this.dayInYear() > d.dayInYear() || this.dayInYear() == d.dayInYear() || this.year > d.year) { return false; }
else { return false; }
}
/** Determines whether this Date is after the Date d.
* @return true if and only if this Date is after d.
*/
public boolean isAfter(Date d) {
return d.isBefore(this);
}
/** Returns the number of this Date in the year.
* @return a number n in the range 1...366, inclusive, such that this Date
* is the nth day of its year. (366 is only used for December 31 in a leap
* year.)
*/
public int dayInYear() {
int noOfdays = 0;
for (int tmonth = 1; month>tmonth; tmonth++) {
noOfdays = noOfdays + daysInMonth(tmonth, this.year); }
noOfdays = noOfdays + this.day;
return noOfdays; }
/** Determines the difference in days between d and this Date. For example,
* if this Date is 12/15/1997 and d is 12/14/1997, the difference is 1.
* If this Date occurs before d, the result is negative.
* @return the difference in days between d and this date.
*/
public int difference(Date d) {
if (this.year == d.year) { return d.dayInYear() - this.dayInYear(); }
else if (this.year < d.year) {
int days = 0;
for (int start = this.year+1; start<d.year; start++) {
days = days + new Date(12, 31, start).dayInYear(); }
return (-1 * (d.dayInYear() + new Date(12,31,this.year).dayInYear() - this.dayInYear() + days)); }
else {
int days = 0;
for (int start = d.year+1; start<this.year; start++) {
days = days + new Date(12, 31, start).dayInYear(); }
return this.dayInYear() + new Date(12,31,d.year).dayInYear() - d.dayInYear() + days; }
}
public static void main(String[] argv) {
System.out.println("\nTesting constructors.");
Date d1 = new Date(1, 1, 1);
System.out.println("Date should be 1/1/1: " + d1);
d1 = new Date("2/4/2");
System.out.println("Date should be 2/4/2: " + d1);
d1 = new Date("2/28/2000");
System.out.println("Date should be 2/28/2000: " + d1);
d1 = new Date("2/29/1904");
System.out.println("Date should be 2/29/1904: " + d1);
d1 = new Date(12, 31, 1975);
System.out.println("Date should be 12/31/1975: " + d1);
Date d2 = new Date("1/1/1976");
System.out.println("Date should be 1/1/1976: " + d2);
Date d3 = new Date("1/2/1976");
System.out.println("Date should be 1/2/1976: " + d3);
Date d4 = new Date("2/27/1977");
Date d5 = new Date("8/31/2110");
/* I recommend you write code to test the isLeapYear function! */
System.out.println("\nTesting before and after.");
System.out.println(d2 + " after " + d1 + " should be true: " +
d2.isAfter(d1));
System.out.println(d3 + " after " + d2 + " should be true: " +
d3.isAfter(d2));
System.out.println(d1 + " after " + d1 + " should be false: " +
d1.isAfter(d1));
System.out.println(d1 + " after " + d2 + " should be false: " +
d1.isAfter(d2));
System.out.println(d2 + " after " + d3 + " should be false: " +
d2.isAfter(d3));
System.out.println(d1 + " before " + d2 + " should be true: " +
d1.isBefore(d2));
System.out.println(d2 + " before " + d3 + " should be true: " +
d2.isBefore(d3));
System.out.println(d1 + " before " + d1 + " should be false: " +
d1.isBefore(d1));
System.out.println(d2 + " before " + d1 + " should be false: " +
d2.isBefore(d1));
System.out.println(d3 + " before " + d2 + " should be false: " +
d3.isBefore(d2));
System.out.println("\nTesting difference.");
System.out.println(d1 + " - " + d1 + " should be 0: " +
d1.difference(d1));
System.out.println(d2 + " - " + d1 + " should be 1: " +
d2.difference(d1));
System.out.println(d3 + " - " + d1 + " should be 2: " +
d3.difference(d1));
System.out.println(d3 + " - " + d4 + " should be -422: " +
d3.difference(d4));
System.out.println(d5 + " - " + d4 + " should be 48762: " +
d5.difference(d4));
}
}
