Common Java Date Method collection (Part Two)

6.Java date computes the number of interval days between two arbitrary times (this comparison is common):

(1) The Calendar object is passed in:

public int getintervaldays (Calendar startday,calendar endday) ... {
if (Startday.after (endday)) ...　　{
Calendar cal=startday;　　
Startday=endday;　　
endday=cal;　　　　
}
Long Sl=startday.gettimeinmillis ();　　
long El=endday.gettimeinmillis ();　　　　　　　　　　　　　
long EI=EL-SL;　　return
(int) (ei/(1000*60*60*24));
}　　　　　

(2) The Date object is passed in:

public int getintervaldays (Date startday,date endday) ... {
if (Startday.after (endday)) ...　　{
Date cal=startday;　　
Startday=endday;　　
endday=cal;　　　　
}
Long Sl=startday.gettime ();　　　　　　　　　
long El=endday.gettime ();　　　　　　　　　　　　　
long EI=EL-SL;　　return
(int) (ei/(1000*60*60*24));
}

(3) Improve the precise calculation of the number of days apart:

public int Getdaysbetween (Calendar d1, calendar D2) ... {
if (D1.after (D2)) ...　　{
Java.util.Calendar swap = D1;　　
D1 = d2;　　
d2 = swap;　　　　
}
int days = D2.get (calendar.day_of_year)-D1.get (calendar.day_of_year);　　
int y2 = d2.get (calendar.year);
if (D1.get (calendar.year)!= y2) ...　　{
D1 = (Calendar) d1.clone (); Do
... {
days = D1.getactualmaximum (calendar.day_of_year);//Get the actual day of the year
D1.add (Calendar .　　year, 1);　　While
(D1.get (calendar.year)!= y2);　　　　
}
return days;
}

Note: The above method can be derived to ask for any time, such as to find out the mailbox within three weeks of mail received (get the current system time-and then get three weeks ago) with the time of the collection to match the best fitted into a long to compare.

such as: 1 years ago Date (note milliseconds conversion):

Java.util.Date mydate=new java.util.Date ();　　
Long Mytime= (Mydate.gettime ()/1000) -60*60*24*365;　　
Mydate.settime (mytime*1000);
String Mdate=formatter.format (mydate);