Joomla calendar field issue

Question

I create a plugin in k2, which has a calendar field.
When I choose the time in k2 backend like 2019-03-13 05:00 and save the item, the time auto becomes 2019-03-13 13:00,the date is correct but the time it's always 8 hours later in the field.

<field 
    name="item_gc_endtime"
    type="calendar"
    default=""
    label="choose"
    description=""
    class="input-medium"
    format="%Y-%m-%d %H:%M"
    singleheader="true"
    showtime="true"
    timeformat="24"
    weeknumbers="true"
    filltable="true"
    maxyear="5" 
/>  

Answer 1

after save the time also become 2019-03-13 13:00,now the problem solved,i only use date field without time,and use the text field for user to input hour

Answer 2

Joomla! converts dates to UTC for database storage. When pulling from the db for display, use the JHtml::('date',...) function or use the timezone method of the JDate object to convert back to your configured timezone and format date output.

Example 1:

echo JHtml::_('date', $item->created, 'Y-m-d G:i:s A');

Example 2:

$config = JFactory::getConfig();
$tz = new DateTimeZone( $config->get('offset') ); // Joomla!'s configured tz
$date = new JDate( $item->created, 'UTC' );
$date->setTimezone($tz); // apply offset
echo $date->format('Y-m-d G:i:s A', true); // true for local time