Java Date and Calendar examples

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最新推荐文章于 2025-09-10 22:21:01 发布

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本文详细介绍了如何使用Java的Date和Calendar API进行日期和时间操作，包括日期转换、获取当前日期时间、手动设置日期、日期加减运算等实用示例。

Java Date and Calendar examples

This tutorial shows you how to work with java.util.Date and java.util.Calendar.

1. Java Date Examples
Few examples to work with Date APIs.

Example 1.1 – Convert Date to String.

SimpleDateFormat sdf = new SimpleDateFormat("dd/M/yyyy");
String date = sdf.format(new Date());
System.out.println(date); //15/10/2013

Example 1.2 – Convert String to Date.

SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
String dateInString = "31-08-1982 10:20:56";
Date date = sdf.parse(dateInString);
System.out.println(date); //Tue Aug 31 10:20:56 SGT 1982

P.S Refer to this – SimpleDateFormat JavaDoc for detail date and time patterns.

Example 1.3 – Get current date time

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date)); //2013/10/15 16:16:39

Example 1.4 – Convert Calendar to Date

Calendar calendar = Calendar.getInstance();
Date date = calendar.getTime();
2. Java Calendar Examples
Few examples to work with Calendar APIs.

Example 2.1 – Get current date time

SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");
Calendar calendar = new GregorianCalendar(2013,0,31);
System.out.println(sdf.format(calendar.getTime()));

Output

2013 Jan 31 00:00:00

Example 2.2 – Simple Calendar example

SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");
Calendar calendar = new GregorianCalendar(2013,1,28,13,24,56);

int year = calendar.get(Calendar.YEAR);
int month = calendar.get(Calendar.MONTH); // Jan = 0, dec = 11
int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK);
int weekOfYear = calendar.get(Calendar.WEEK_OF_YEAR);
int weekOfMonth= calendar.get(Calendar.WEEK_OF_MONTH);

int hour = calendar.get(Calendar.HOUR); // 12 hour clock
int hourOfDay = calendar.get(Calendar.HOUR_OF_DAY); // 24 hour clock
int minute = calendar.get(Calendar.MINUTE);
int second = calendar.get(Calendar.SECOND);
int millisecond= calendar.get(Calendar.MILLISECOND);

System.out.println(sdf.format(calendar.getTime()));

System.out.println("year \t\t: " + year);
System.out.println("month \t\t: " + month);
System.out.println("dayOfMonth \t: " + dayOfMonth);
System.out.println("dayOfWeek \t: " + dayOfWeek);
System.out.println("weekOfYear \t: " + weekOfYear);
System.out.println("weekOfMonth \t: " + weekOfMonth);

System.out.println("hour \t\t: " + hour);
System.out.println("hourOfDay \t: " + hourOfDay);
System.out.println("minute \t\t: " + minute);
System.out.println("second \t\t: " + second);
System.out.println("millisecond \t: " + millisecond);

Output

2013 Feb 28 13:24:56
year : 2013
month : 1
dayOfMonth : 28
dayOfWeek : 5
weekOfYear : 9
weekOfMonth : 5
hour : 1
hourOfDay : 13
minute : 24
second : 56
millisecond : 0

Example 2.3 – Set a date manually.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");

Calendar calendar = new GregorianCalendar(2013,1,28,13,24,56);
System.out.println("#1. " + sdf.format(calendar.getTime()));

//update a date
calendar.set(Calendar.YEAR, 2014);
calendar.set(Calendar.MONTH, 11);
calendar.set(Calendar.MINUTE, 33);

System.out.println("#2. " + sdf.format(calendar.getTime()));

Output

#1. 2013 Feb 28 13:24:56
#2. 2014 Dec 28 13:33:56

Example 2.4– Add or subtract from a date.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd");

Calendar calendar = new GregorianCalendar(2013,10,28);
System.out.println("Date : " + sdf.format(calendar.getTime()));

//add one month
calendar.add(Calendar.MONTH, 1);
System.out.println("Date : " + sdf.format(calendar.getTime()));

//subtract 10 days
calendar.add(Calendar.DAY_OF_MONTH, -10);
System.out.println("Date : " + sdf.format(calendar.getTime()));

Output

Date : 2013 Nov 28
Date : 2013 Dec 28
Date : 2013 Dec 18

Example 2.5– Convert Date to Calendar.

SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
String dateInString = "22-01-2015 10:20:56";
Date date = sdf.parse(dateInString);

Calendar calendar = Calendar.getInstance();
calendar.setTime(date);

https://www.mkyong.com/java/java-date-and-calendar-examples/
http://www.mkyong.com/tutorials/java-date-time-tutorials/