Java Date Time in Java 8
java 1.0 |
java.util.Date;java.text.Format |
java 1.2 |
java.util.Calendar |
java 8 |
java.time.* |
java 8 classes: LocalDate, LocalTime, LocalDateTime, Month (1-12), Period, Duration
Creating Dates and Times
static of() |
Overriden by LocalData, LocalTime and LocalDateTime |
LocalDate.of(y,m.d); |
m: int or Month(1-12) |
LocalTime.of(h,mi,s,ns) |
ns: nano second |
LocalDateTime.of(y,m,d,h,mi,s,ns) |
LocalDateTime.of(d,t) |
static now() |
Overriden by LocalData, LocalTime and LocalDateTime |
static parse(s,f) |
Overriden by LocalData, LocalTime and LocalDateTime |
LocalDateTime.parse(s,f) |
f must be DateTimeFormatter |
LocalDate d= new LocalDate() //not compiled
LocalDate d= LocalDate.of(2015,2,30); //not compile
Manipulating Dates and Times
plusXxx(int) |
minusXxx(int) |
return new immutable, original not changed, like String |
chain of method on date and time |
getXxx(); //Xxx= DayOfWeek,DayOfYear, Month, Year |
dt1.isBefore(dt2) |
dt1.isAfter(dt2) |
Xxx= Years / Months /Days/Hours/Minutes/Seconds/Nanos;
Java 8 date & time are immutable, like String objects.
|
|
Peroid and Duration
java.time.Period; Java.time.Duration; |
4 ways to create a period |
Period.ofXxx(int); //Xxx=Years,Months,Days |
Period.of(int years,int months, int days); |
Period.between (d1,d2) |
Period.parse("P1Y2M3W4D");//same as Period.of(1, 2, 25) |
Modify period |
plusXxx(int); //Days|Weeks|Months|Years |
minusXxx(int) |
Use period |
dt.plus/minnus(period); |
d.plus/minus(period); |
time.plus/minus(duration); //if input period, UnsupportedTemporalTypeException |
Chain of Periods method does not make sense and raise compiler error
Formatting
2 methods to create a formatter |
DateTimeFormatter f=DateTimeFormatter.ofXxx
(FormatStyle.SHORT|MEDIUM|LONG|FULL); |
DateTimeFormatter f=DateTimeFormatter.ofPattern
("yyyy-MMMM-dd hh:mm:ss"); //M 1 MM 01 MMM Jan MMMM January |
Standard formatter: |
DateTimeFormatter.ISO_LOCAL_DATE/TIME/DATETIME |
ISO_LOCAL_DATETIME: '2011-12-03T10:15:30' |
3 ways to use formatter |
f.format( date/time/datetime_obj ); |
date/time/datetime_obj.format( f ); |
LocalDate/Time/DateTime.parse(String s, DateTimeFormatter f); |
1 Xxx = LocalizedDate, LocalizedTime,LocalizedDateTime
2 date and time format legal for datatime object, datatime format not legal for date or time object
|
