Conversion between date and calendar

1. Conversion between date and calendar:

 

Java code

1. Date = new date ();
2. Calendar calendar = calendar. getinstance ();
3. Calendar. settime (date );
4. Calendar. Add (calendar. Date,-1); // obtain the previous day
5. Calendar. Add (calendar. Month,-1); // obtain the previous month.
6. 
   

In this way, the calendar instance can be used to obtain the date and time.

 

2. Conversion between date and string:

 

Java code

1. String datestr = "2008-8-13 ";
2. String Pattern = "yyyy-mm-dd ";
3. Dateformate dateformat = new simpledateformat (pattern );
4. Date = dateformat. parse (datestr );
5. Date = dateformat. Format (date );

In this way, the instance date of a date can be converted to the calendar ar type, and then the date operation is performed.

3. Convert calendar to date

Calendar CA = calendar. getinstance ();

Date Ss = (date) Ca. gettime ();

4. the query date range cannot exceed one month

Import java. util. date;

Import java. util. calendar;

Import java. Text. simpledateformat;

Import java. Text. dateformat;

String start = '2017-01-02'

String end = '2017-02-12'

Dateformat = new simpledateformat ("yyyy-mm-dd ");

Try {

Date startdate = dateformat. parse (start );

Date enddate = datefformat. parse (end );

Calendar Cal = calendar. getinstance ();

Cal. settime (startdate );

Cal. Add (calendar. Month, + 1 );

Startdate = (date) Cal. gettime ();

If (startdate. gettime () <enddate. gettime ()){

Return "the query date range cannot exceed one month ";

} Catch (parseexception e ){

E. printstacktrace ();

}