java - Set time to 00:00:00 -

i have problem resetting hours in java. given date want set hours 00:00:00.

this code :

/**      * resets milliseconds, seconds, minutes , hours provided date      *      * @param date      * @return      */     public static date trim(date date) {         calendar calendar = calendar.getinstance();         calendar.settime(date);         calendar.set(calendar.millisecond, 0);         calendar.set(calendar.second, 0);         calendar.set(calendar.minute, 0);         calendar.set(calendar.hour, 0);          return calendar.gettime();     } 

the problem time 12:00:00 , 00:00:00 , when query database entity saved on 07.02.2013 00:00:00 , actual entity time, stored, 12:00:00 query fails.

i know 12:00:00 == 00:00:00!

i using appengine. appengine bug, problem or other issue? or depend on else?

use constant instead of calendar.hour, use calendar.hour_of_day.

calendar.set(calendar.hour_of_day, 0); 

calendar.hour uses 0-11 (for use am/pm), , calendar.hour_of_day uses 0-23.

to quote javadocs:

public static final int hour

field number , set indicating hour of morning or afternoon. hour used 12-hour clock (0 - 11). noon , midnight represented 0, not 12. e.g., @ 10:04:15.250 pm hour 10.

and

public static final int hour_of_day

field number , set indicating hour of day. hour_of_day used 24-hour clock. e.g., @ 10:04:15.250 pm hour_of_day 22.

testing ("now" c. 14:55 on july 23, 2013 pacific daylight time):

public class main {    static simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");      public static void main(string[] args)     {         calendar = calendar.getinstance();         now.set(calendar.hour, 0);         now.set(calendar.minute, 0);         now.set(calendar.second, 0);         system.out.println(sdf.format(now.gettime()));         now.set(calendar.hour_of_day, 0);         system.out.println(sdf.format(now.gettime()));     } } 

output:

$ javac main.java $ java main 2013-07-23 12:00:00 2013-07-23 00:00:00