I have to calculate the number of days between two dates the hard way.
I know there is already a way to do this with an existing package and such but I have to do it within a single method "daysBetween" without altering any other part of the code.
The method must be able to return a positive/negative value depending what start/end dates it is given and also take into account leap years and such.
What I have right now in the "daysBetween" method starting on line 258 DOES NOT WORK and can be completely scrapped if necessary.
(I know its long, i'm sorry but i didn't know what you might need)
The "daysBetween" method starts on line 258
import java.util.Calendar;
import java.util.GregorianCalendar;
public class Date implements Proj1Constants {
private static final int[] DAYS = { 0, 31, 29, 31, 30, 31, 30, 31, 31,
30, 31, 30, 31 };
private static final int LEAP_YEAR = 366;
private static final int NON_LEAP_YEAR = 365;
private final int month; // month (between 1 and 12)
private final int day; // day (between 1 and DAYS[month])
private final int year; // year
/**
* Constructor: default; returns today's date
*/
// creates today's date as the date; obtains it from Java library
public Date() {
GregorianCalendar c = new GregorianCalendar();
month = c.get(Calendar.MONTH)+1; //our month starts from 1
day = c.get(Calendar.DAY_OF_MONTH);
year = c.get(Calendar.YEAR);
}
/**
* Constructor: Does bounds-checking to ensure object represents a valid
* date
*
* @param m represents the month between 1 and 12
* @param d represents the date between 1 and the corresponding number
* from array DAYS
* @param y represents the year
* @exception RuntimeException
* if the date is invalid
*/
public Date(int m, int d, int y) {
if (!isValid(m, d, y))
throw new RuntimeException("Invalid date");
month = m;
day = d;
year = y;
}
/**
* Constructor: Does bounds-checking to ensure string represents a valid
* date
*
* @param sDate represents a date given in format mm-dd-yyyy
* @exception RuntimeException if the date is invalid
*/
public Date(String sDate) {
int m, d, y;
String[] chopDate = sDate.split("-");
m = Integer.parseInt(chopDate[ZEROI]);
d = Integer.parseInt(chopDate[ONEI]);
y = Integer.parseInt(chopDate[TWOI]);
if (!isValid(m, d, y))
throw new RuntimeException("Invalid date");
month = m;
day = d;
year = y;
}
/**
* constructor: creates a date with a given year; fills in valid month and day;
* as december 31st.
*
* @param y represents a date given in year as integer
*/
public Date(int y) {
month = 12;
day = DAYS[12];
year = y;
}
/**
* create a date with a given month and year; fills in valid day;
*
* @param m represents the month between 1 and 12
* @param y represents the year
* @exception RuntimeException if the date is invalid
*/
public Date(int m, int y) {
if (!isValid(m, DAYS[m], y))
throw new RuntimeException("Invalid date; correct input");
month = m;
day = DAYS[m];
year = y;
}
/**
* Is the given date valid?
*
* @param month, day, and year
* @return false if month exceeds 12 or is less than 1
* @return false if day exceeds the corresponding days for a month from
* array DAYS
* @return false if the year is not a leap year and has 29 days
*/
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?
*
* @param y
* represents the year specified
* @return true if year divisible by 400
* @return false if year divisible by 100 and not by 400
*/
private static boolean isLeapYear(int y) {
if (y % 400 == 0)
return true;
if (y % 100 == 0)
return false;
return (y % 4 == 0);
}
/**
* is (m, y) a leap month?
*
* @param m represents the month specified
* @param y represents the year specified
* @return true if it is a leap month
* @return false otherwise
*/
private static boolean isLeapMonth(int m, int y) {
if (isLeapYear(y)) return ((m == 2) ? true : false);
return false;
}
// return the next Date
/**
* adds a day and returns a new Date object
*
* @return returns a new Date object adding a 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?
/**
* compares two Date objects
*
* @param b Date object
* @return true if this Date is after Date b
*/
public boolean isAfter(Date b) {
return compareTo(b) > 0;
}
// is this Date a before b?
/**
* compares two date objects
*
* @param b Date object
* @return true if this Date is before Date b
*/
public boolean isBefore(Date b) {
return compareTo(b) < 0;
}
// comparison function between two dates
/**
* compares two Date objects
*
* @param b Date object
* @return 0 if this Date is the same as Date b <br>
* negative integer if this Date is earlier than Date b <br>
* positive integer if this Date is after Date b
*/
public int compareTo(Date b) {
if (year != b.year)
return year - b.year;
if (month != b.month)
return month - b.month;
return day - b.day;
}
// advance date by number of months
/**
* advances the date by m months
*
* @param m represents the months to advance
* @return new Date object (as the original object is immutable)
*/
public Date addMonths(int m) {
int newMonth, newYear, newDay;
newMonth = month + m;
if (newMonth > 12){
newMonth = (month + m)%12;
}
newYear = (int)((month + m)/12);
if(!isValid(newMonth, day,year + newYear)){
if(newMonth == 2){
if(isLeapMonth(newMonth, year + newYear)){
newDay = DAYS[newMonth];
}
else{
newDay = DAYS[newMonth]-1;
}
}
else
newDay = DAYS[newMonth];
return new Date(newMonth,newDay,year + newYear);
}
else
return new Date(newMonth, day, year + newYear);
}
// subtracts two dates to return the difference in full months
/**
* @param endDate represents the second date
* @return int months - the difference between the two dates
*/
public int monthsBetween(Date endDate) {
//complete this method
return ((endDate.month - month)+(endDate.year - year)*12);
}
// returns the number of days between two date
/**
* @ param endDate is the second date
* @ return the number of days between two dates
* - 1 if start date is after the end date
* 0 if start date is equal to the end date
* + #days if the start date is before end date
*
*/
public int daysBetween(Date endDate) {
int currentYear=year, currentMonth=month, dayCount=0, i;
if(isAfter(endDate)){
if(!isLeapYear(year) && month == 2){
for (i=day;i<=DAYS[currentMonth]-1;i++){
dayCount += 1;
}
}
else{
for (i=day;i<=DAYS[currentMonth];i++){
dayCount +=1;
}
}
System.out.println("from ["+month+"-"+day+"-"+year+"] to next month is "+dayCount);
while(endDate.year != year && endDate.month != month ){
for (i=0;i<DAYS[currentMonth];i++){
dayCount += 1;
}
currentMonth += 1;
if(currentMonth > 12){
currentYear += 1;
currentMonth = 1;
System.out.println("Advancing to month "+ currentMonth+"-"+currentYear);
}
}
}
else
dayCount = 123; // I did this so that I could run the program and avoid (-) values for now
return dayCount;
}
// return a string representation of this date
/**
* replaces the default toString of Object class
*/
public String toString() {
return "[" + month + "-" + day + "-" + year + "]";
}
// sample client for testing
/**
* Code for testing the Date class
*
* @param args Array of String arguments
*/
public static void main(String[] args) {
Date today = new Date(2, 26, 2012);
System.out.println("Input date is " + today);
System.out.println("Printing the next 10 days after " + today);
for (int i = 0; i < 10; i++) {
today = today.next();
System.out.println(today);
}
Date expiry = new Date(2011);
System.out.println("testing year 2011 as input:" + expiry);
Date todayDate = new Date(9,6,2011);
System.out.println("todays date: " + todayDate);
System.out.println("current month:" + todayDate.month);
// testing isValidMonth function
Date start = new Date("08-01-2010");
Date end1 = new Date("09-01-2010");
Date lease = new Date("1-01-2012");
Date expiry1 = new Date("12-31-2012");
// testing daysBetween
System.out
.println("\nTESTING daysBetween method\n------------------------------");
int count = lease.daysBetween(expiry);
System.out.println("Days between " + lease + " and " + expiry + "is: "
+ count);
count = new Date("1-01-2011").daysBetween(new Date("12-31-2011"));
System.out.println("Days between [1-01-2011] and [12-31-2011]" + "is: "
+ count);
count = lease.daysBetween(expiry1);
System.out.println("Days between " + lease + " and " + expiry1 + "is: "
+ count);
Date testDate = new Date("12-31-2013");
count = lease.daysBetween(testDate);
System.out.println("Days between " + lease + " and [12-31-2013] "
+ "is: " + count);
count = lease.daysBetween(lease);
System.out.println("Days between " + lease + " and " + lease + "is: "
+ count);
count = lease.daysBetween(new Date("1-10-2012"));
System.out.println("Days between " + lease + " and [1-10-2012" + "is: "
+ count);
count = testDate.daysBetween(lease);
System.out.println("Days between " + testDate + " and " + lease + "is: "
+ count);
// testing isBefore
System.out
.println("\nTESTING isBefore method\n------------------------------");
boolean isBefore = today.isBefore(today.next());
System.out.println(today + "is before " + today.next() + ": "
+ isBefore);
isBefore = today.next().isBefore(today);
System.out.println(today.next() + "is before " + today + ": "
+ isBefore);
isBefore = today.isBefore(today);
System.out.println(today + "is before " + today + ": " + isBefore);
isBefore = today.isBefore(today.addMonths(12));
System.out.println(today + "is before " + today.addMonths(12) + ": " + isBefore);
// testing addMonths
System.out
.println("\nTESTING addMonths method\n------------------------------");
today = new Date("1-31-2011");
Date newDate = today.addMonths(1);
System.out
.println("adding 1 months to " + today + " gives: " + newDate);
newDate = today.addMonths(13);
System.out.println("adding 13 months to " + today + " gives: "
+ newDate);
today = new Date("3-31-2010");
newDate = today.addMonths(15);
System.out.println("adding 15 months to " + today + " gives: "
+ newDate);
newDate = today.addMonths(23);
System.out.println("adding 23 months to " + today + " gives: "
+ newDate);
newDate = today.addMonths(49);
System.out.println("adding 49 months to " + today + " gives: "
+ newDate);
newDate = today.addMonths(0);
System.out
.println("adding 0 months to " + today + " gives: " + newDate);
// testing monthsBetween
System.out
.println("\nTESTING monthsBetween method\n------------------------------");
int monthDiff = today.monthsBetween(today.addMonths(1));
System.out.println("months between " + today + " and " + today.addMonths(1)
+ ": " + monthDiff);
monthDiff = today.next().monthsBetween(today);
System.out.println("months between " + today.next() + " and " + today
+ ": " + monthDiff);
today = new Date("09-30-2011");
Date endDate = new Date("2-29-2012");
monthDiff = today.monthsBetween(endDate);
System.out.println("months between " + today + " and " + endDate + ": "
+ monthDiff);
today = new Date();
Date endDate1 = new Date("12-04-2011");
monthDiff = today.monthsBetween(endDate1);
System.out.println("months between " + today + " and " + endDate1
+ ": " + monthDiff);
today = new Date();
Date endDate2 = new Date("12-22-2010");
monthDiff = today.monthsBetween(endDate2);
System.out.println("months between " + today + " and " + endDate2
+ ": " + monthDiff);
// following should generate exception as date is invalid!
// today = new Date(13, 13, 2010);
// expiry = new Date("2-29-2009");
// newDate = today.addMonths(-11);
}
}
