import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class Mytest {         /**      * @param args      */     public static void main(String[] args)     {         // TODO Auto-generated method stub         String date1 = "2009-03-23 08:00:00";//指定时间         String date2=  addDate(date1,15);//加1小时方法         System.out.println("after:"+date2);          }         public static String addDate(String day, int x)     {         SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//24小时制         //SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");//12小时制         Date date = null;         try         {             date = format.parse(day);         }         catch (Exception ex)            {             ex.printStackTrace();         }         if (date == null) return "";         Calendar cal = Calendar.getInstance();         cal.setTime(date);         cal.add(Calendar.HOUR_OF_DAY, x);//24小时制         //cal.add(Calendar.HOUR, x);12小时制         date = cal.getTime();         System.out.println("front:" + date);         cal = null;         return format.format(date);     }     }