Calendar、Date、long類型的時間，三者之間如何轉化

1. Calendar類型轉化為Date類型和long類型

Calendar calendar=Calendar.getInstance();
Date date=calendar.getTime();
long time=calendar.getTimeInMillis();

2.Date類型轉化為Calendar類型和long類型

Date date=new Date(System.currentTimeMillis()[phone]);
Calendar calendar=Calendar.getInstance();
calendar.setTime(date);
long time=date.getTime();

3. long類型轉化為Date類型和Calendar類型

long time=System.currentTimeMillis()[phone];
Date date=new Date(time);
Calendar calendar=Calendar.getInstance();
calendar.setTimeInMillis(time);