常用类之日期(Date Calendar)
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class DateAndCalendarTest
{
public static void main(String[] args)
{
//Date类对象表示当前日期和时间
//划横线的为过时的方法 就是java不建议再使用的
Date nowDate=new Date();
System.out.println("当前年:"+(nowDate.getYear()+1900));
System.out.println("当前月:"+(nowDate.getMonth()+1));
System.out.println("当前日:"+nowDate.getDate());
System.out.println("当前星期:"+nowDate.getDay());
System.out.println("当前时:"+nowDate.getHours());
System.out.println("当前分:"+nowDate.getMinutes());
System.out.println("当前秒:"+nowDate.getSeconds());
System.out.println("从1970年1月1日起到现在的毫秒:"+nowDate.getTime());
System.out.println("现在的时间是:"+nowDate.toString());
System.out.println("现在的时间是(本地格式):"+nowDate.toLocaleString());
System.out.println("现在的时间是(格林威治时间格式):"+nowDate.toGMTString());
System.out.println("================================");
//常用的时间格式 和 对应方法
//其中yyyy-MM-dd是你要表示的格式
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String systemtime=sdf.format(nowDate);
System.out.println(systemtime);
sdf=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
systemtime=sdf.format(nowDate);
System.out.println(systemtime);
System.out.println("================================");
//时间性能测试,测试代码运行的时间
long startTime=new Date().getTime();
//这里是你自己的方法
long endTime=new Date().getTime();
System.out.println("程序执行用时:"+(endTime-startTime)+"毫秒");
System.out.println("================================");
System.out.println("当前年:"+Calendar.getInstance().get(Calendar.YEAR)); //返回默认地区和时区的Calendar对象
System.out.println("当前月:"+Calendar.getInstance().get(Calendar.MONTH)+1);
System.out.println("当前日(月中的):"+Calendar.getInstance().get(Calendar.DAY_OF_MONTH));
System.out.println("当前日(年中的):"+Calendar.getInstance().get(Calendar.DAY_OF_YEAR));
System.out.println("当前星期:"+Calendar.getInstance().get(Calendar.DAY_OF_WEEK)); //周日是第一天
System.out.println("当前时:"+Calendar.getInstance().get(Calendar.HOUR_OF_DAY));
System.out.println("当前分:"+Calendar.getInstance().get(Calendar.MINUTE));
System.out.println("当前秒:"+Calendar.getInstance().get(Calendar.SECOND));
System.out.println("================================");
Calendar muBirthday = Calendar.getInstance();
muBirthday.set(Calendar.YEAR, 1986);
muBirthday.set(Calendar.MONTH, 3);
muBirthday.set(Calendar.DAY_OF_MONTH,19);
System.out.println("我的生日是在一年中的第:"+muBirthday.get(Calendar.DAY_OF_YEAR)+"天");
System.out.println("我的生日是:"+(new Date(muBirthday.getTimeInMillis())).toLocaleString());
System.out.println("================================");
Calendar calObj = Calendar.getInstance();
calObj.add(Calendar.YEAR, 1);
System.out.println("1年后:"+calObj.getTime().toLocaleString());
}
}