時間型データの演算

  Calendar add(int field, int amount)  。 : 
 
 
import java.text.ParseException;
 
import java.text.SimpleDateFormat;
 
import java.util.Calendar;
 
public class TestCalendar {
 
 
 publicstatic void main(String[] args){
 
 Calendar c = Calendar.getInstance();
 
 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 
 try{
 
// 
 
Date date=format.parse("2011-08-05 14:49:45");
 
 c.setTime(format.parse("2011-08-05 14:49:45"));
 
 System.out.println(" :"+format.format(c.getTime()));
 
 c.add(Calendar.MINUTE,20);
 
 System.out.println(" :"+format.format(c.getTime()));
 
 }catch (ParseException e) {
 
 e.printStackTrace();
 
 }
 
 }
 
}
 

 
 ：
 
Date today = new Date();
SimpleDateFormat df = new SimpleDateFormat(DateUtil.getDatePattern());
createDate = df.format(today);
 

 

 
 ， ， 。
 
public static int getDay(Date date) {
if (date == null) {
return 0;
}
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
return calendar.get(Calendar.DAY_OF_YEAR);
 }