Solved

# java.sql.date calculations

Posted on 2001-06-14
1,157 Views
hi,
i wanted to know how do you calculate the number of days between two dates in java ? i get both the dates from the database. i guess there are many issues like leap year and Febuary having diff no of months ..etc.

a sample code with just be great.

Thanks
0
Question by:pravin_tiwari

LVL 3

Expert Comment

ID: 6193275
Date d1, d2;

int days =(int)(  (d1.getTime()-d2.getTime()) / 86400000 );

getTime() returns the number of milliseconds since January 1, 1970, 00:00:00 GMT.
86400000 == 24 * 60 * 60 * 1000
0

LVL 2

Expert Comment

ID: 6193312
The problem with the above sample is it doesn't work for dates before the year 1970.

Here is the code with traditional logic, which doesn't use any library methods provided by java.  It works for all dates.

U can use which ever solution u want depending on your requirement.

public class DiffDates {

public boolean chkleap(int year) {
boolean isLeap = false;
if ((year % 4) == 0) {
isLeap = true;
}

if (((year % 100) == 0) && ((year % 400) != 0)) {
isLeap = false;
}

return isLeap;
}//end of chkleap()

public DiffDates() {
int M[]={0,31,28,31,30,31,30,31,31,30,31,30,31};

int i=0,j=0,k=0;
long count=0;

int d1=13, d2=14;
int m1=6,m2=6;
int y1=1975,y2=2001;

/*
To find difference between 13 th June 1975 and 14 th June 2001.
d1 = 13, m1 = 6, y1 = 1975
d2 = 14, m2 = 6, y2 = 2001
*/

if (y1!=y2) {
for (i=y1;i<y2;i++) {
if (chkleap(i)) count+=366;
else count+=365;
}
}

if (chkleap(y1)) M[2]=29;

k=d1;

if (m1!=1) {
for (i=1;i<m1;i++)
k+=M[i];
}

if (chkleap(y2)) M[2]=29;
else M[2]=28;

j=d2;

if (m2!=1) {
for (i=1;i<m2;i++)
j+=M[i];
}

count = count + (j - k);

System.out.println("The difference between two given dates is: " + count + " Days");
}//end of constructor

public static void main(String args[]) {
new DiffDates();
}//end of main()
}//end of class DiffDates
0

LVL 2

Expert Comment

ID: 6193348
The problem with the above sample is it doesn't work for dates before the year 1970.

Here is the code with traditional logic, which doesn't use any library methods provided by java.  It works for all dates.

U can use which ever solution u want depending on your requirement.

public class DiffDates {

public boolean chkleap(int year) {
boolean isLeap = false;
if ((year % 4) == 0) {
isLeap = true;
}

if (((year % 100) == 0) && ((year % 400) != 0)) {
isLeap = false;
}

return isLeap;
}//end of chkleap()

public DiffDates() {
int M[]={0,31,28,31,30,31,30,31,31,30,31,30,31};

int i=0,j=0,k=0;
long count=0;

int d1=13, d2=14;
int m1=6,m2=6;
int y1=1975,y2=2001;

/*
To find difference between 13 th June 1975 and 14 th June 2001.
d1 = 13, m1 = 6, y1 = 1975
d2 = 14, m2 = 6, y2 = 2001
*/

if (y1!=y2) {
for (i=y1;i<y2;i++) {
if (chkleap(i)) count+=366;
else count+=365;
}
}

if (chkleap(y1)) M[2]=29;

k=d1;

if (m1!=1) {
for (i=1;i<m1;i++)
k+=M[i];
}

if (chkleap(y2)) M[2]=29;
else M[2]=28;

j=d2;

if (m2!=1) {
for (i=1;i<m2;i++)
j+=M[i];
}

count = count + (j - k);

System.out.println("The difference between two given dates is: " + count + " Days");
}//end of constructor

public static void main(String args[]) {
new DiffDates();
}//end of main()
}//end of class DiffDates
0

LVL 2

Expert Comment

ID: 6193371
Sorry for posting the same answer twice.  But it is not my mistake.  I have just pressed the refresh button of the browser.

Coming back to the above solution, u have to make sure that first date(d1, m1, y1) comes before the second date(d2, m2, y2).  To do so, u can use compareTo() method in java.util.Date class (or) u can write your own logic.
0

LVL 3

Expert Comment

ID: 6194114
hi there....
i got another example here...
hope it helps...:)

first of all, conver the 2 date(String) to Calendar obj...
then

int DayDiff(Calendar y,Calendar z)
{
int counter=0;

while(true)
{
Holiday a = new Holiday(y);

if (y.get(Calendar.DATE)==z.get(Calendar.DATE) &&
y.get(Calendar.MONTH)==z.get(Calendar.MONTH) &&
y.get(Calendar.YEAR)==z.get(Calendar.YEAR))
{
break;
}

counter++;

y.roll(Calendar.DATE,true);
if (y.get(Calendar.DATE)==1)
{
y.roll(Calendar.MONTH,true);
if (y.get(Calendar.MONTH)==1)
{
y.roll(Calendar.YEAR,true);
}
}
}
return counter;
}

with this codes, u can even add in ur own requirement like exclude sunday or public holiday...:P

0

LVL 3

Accepted Solution

superschlonz earned 200 total points
ID: 6194748
Hi vertical2000

Why do you think my versin doesn't work before 1970 ???

getTime() should return negative values and all should work.

I think the only thing it doesn't do properly are these leap seconds.
0

LVL 1

Expert Comment

ID: 6957050
ADMINISTRATION WILL BE CONTACTING YOU SHORTLY.  Moderators Computer101 or Netminder will return to finalize these if still open in seven days.  Please post closing recommendations before that time.

Question(s) below appears to have been abandoned. Your options are:

1. Accept a Comment As Answer (use the button next to the Expert's name).
2. Close the question if the information was not useful to you, but may help others. You must tell the participants why you wish to do this, and allow for Expert response.  This choice will include a refund to you, and will move this question to our PAQ (Previously Asked Question) database.  If you found information outside this question thread, please add it.
3. Ask Community Support to help split points between participating experts, or just comment here with details and we'll respond with the process.
4. Delete the question (if it has no potential value for others).
--> Post comments for expert of your intention to delete and why
--> YOU CANNOT DELETE A QUESTION with comments; special handling by a Moderator is required.

For special handling needs, please post a zero point question in the link below and include the URL (question QID/link) that it regards with details.
http://www.experts-exchange.com/jsp/qList.jsp?ta=commspt

Click you Member Profile to view your question history and please keep them updated. If you are a KnowledgePro user, use the Power Search option to find them.

Questions which are LOCKED with a Proposed Answer but do not help you, should be rejected with comments added.  When you grade the question less than an A, please comment as to why.  This helps all involved, as well as others who may access this item in the future.  PLEASE DO NOT AWARD POINTS TO ME.

http://www.experts-exchange.com/questions/Q.11583218.html
http://www.experts-exchange.com/questions/Q.20110298.html
http://www.experts-exchange.com/questions/Q.20135782.html
http://www.experts-exchange.com/questions/Q.20135845.html
http://www.experts-exchange.com/questions/Q.20137406.html
http://www.experts-exchange.com/questions/Q.20155091.html
http://www.experts-exchange.com/questions/Q.20155730.html
http://www.experts-exchange.com/questions/Q.20181972.html
http://www.experts-exchange.com/questions/Q.20256001.html
http://www.experts-exchange.com/questions/Q.20262969.html

http://www.experts-exchange.com/questions/Q.20138318.html
http://www.experts-exchange.com/questions/Q.20139584.html

*****  E X P E R T S    P L E A S E  ******  Leave your closing recommendations if this item remains inactive another seven (7) days.  If you are interested in the cleanup effort, please click this link http://www.experts-exchange.com/jsp/qManageQuestion.jsp?ta=commspt&qid=20274643
POINTS FOR EXPERTS awaiting comments are listed here -> http://www.experts-exchange.com/commspt/Q.20277028.html

Moderators will finalize this question if in @7 days Asker has not responded.  This will be moved to the PAQ (Previously Asked Questions) at zero points, deleted or awarded.

Thank you everyone.

Moondancer
Moderator @ Experts Exchange
0

LVL 14

Expert Comment

ID: 8950695

No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

-- points to superschlonz

sudhakar_koundinya
EE Cleanup Volunteer
---------------------
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

### Suggested Solutions

For customizing the look of your lightweight component and making it look lucid like it was made of glass. Or: how to make your component more Apple-ish ;) This tip assumes your component to be of rectangular shape and completely opaque. (COD…
Java had always been an easily readable and understandable language.  Some relatively recent changes in the language seem to be changing this pretty fast, and anyone that had not seen any Java code for the last 5 years will possibly have issues unde…
Viewers learn about the scanner class in this video and are introduced to receiving user input for their programs. Additionally, objects, conditional statements, and loops are used to help reinforce the concepts. Introduce Scanner class: Importing…
The viewer will learn how to implement Singleton Design Pattern in Java.