java time and date

Java time and date

Date class

Two constructors:

• Date(): Use the current time to initialize the object
• Date(long millisec): The parameter is the number of milliseconds since January 1, 1970

Date format:
use SimpleDateFormat format

		Date date=new Date();
        SimpleDateFormat ft=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        System.out.println(ft.format(date));

SimpleDateFormat format:
G year marker
y year
M month
d day
h hour in the morning or afternoon (1~12)
H hour in the day (0~23)
m minutes
s seconds
S milliseconds
E week
D Day of the year Day
F Day of the week in January
w Day of the year
W Week in January
a Morning/afternoon marker
k hour in the day (1~24)
K hour in the morning or afternoon (0 ~11)
z time zone

Calendar class

Calendar is an abstract classCalendar c=Calendar.getInstance();

Common attributes

• static int YEAR
• static int MONTH：0~11
• static int DATE
• static int HOUR: 12-hour clock
• static int HOUR_OF_DAY: 24-hour clock
• static int MINUTE
• static int SECOND
• static int DAY_OF_WEEK: day of the week

Common method

• set(int field,int value):例：c.set(Calendar.MONTH,3);
• get (this is the field)

Implementation class GregorianCalendar

Calendar.getInstance()Is to create and return a GregorianCalendar object.