4，日期

 

package caokangnsd; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; import java.util.logging.SimpleFormatter; public class DateAndClander { /** * 时间API的使用，主要的几个类Date，SimpleDateFormat，Calendar * @throws ParseException  */ public static void main(String[] args) throws ParseException { //1,Date Date date=new Date(); System.out.println(date);//Sat Nov 25 16:21:16 CST 2017 long get=date.getTime(); System.out.println(get);//1511598130112,System.currentTimeMilles(); date.setTime(get+10000); System.out.println(date);//这里在Date类里操作的get，set都是long的毫秒值 //2，SimpleFormatDate /* * here we should know the rules; * y M d E H h a m s * year month day hour am pm minutes second; *  */ SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String str=format.format(date); System.out.println(str); //我们还可以根据字符串来设定date str="2017-11-25 16:35:20"; date=format.parse(str); System.out.println(date); /* * calender内有较多的时间操作 * getTime setTime get set add *  */ Calendar c1=Calendar.getInstance(); System.out.println(c1.getTime());//相当于date c1.setTime(date); System.out.println(c1.getTime());// // int a=c1.get(Calendar.YEAR);//----get System.out.println(a); c1.set(Calendar.YEAR, 2015);//----set System.out.println(c1.getTime()); c1.add(Calendar.YEAR, 2);//-------add System.out.println(c1.getTime()); //另外的Calendar内的常量 System.out.println(""+Calendar.AM+"?"+ Calendar.AM_PM+"?"+ Calendar.DATE+"?"+ Calendar.DAY_OF_MONTH+"?"+ Calendar.DAY_OF_WEEK+"?"+ Calendar.DAY_OF_WEEK_IN_MONTH+"?"+ Calendar.DAY_OF_YEAR+"?"+ Calendar.HOUR+"?"+ Calendar.HOUR_OF_DAY+"?"+ Calendar.WEEK_OF_MONTH+"?"+ Calendar.WEEK_OF_YEAR+"?"+ Calendar.SUNDAY+"?"+//主要注意1 Calendar.JANUARY);//注意一月为0 } }