java.time.Period - Periods in Days and Months

JDK Tutorials - Herong's Tutorial Examples

∟Java Date-Time API

∟java.time.Period - Periods in Days and Months

This section describes the java.time.Period class that represents a calendar period measured in years, months, and/or days.

When manipulating calendar dates, we have to handle calendar periods that are measured in days, months or years. The java.time.Period class in the Date-Time API is designed to help us do this. It represents a calendar period between two given calendar dates. A calendar duration is actually represented by a java.time.Period object with 3 independent components:

Years - Representing the number of years in this period. A 1-year period is equivalent to a 12-month period. But a 1-year period cannot be converted to a period in days, because a 1-year period could be a 365-day period or a 366-day period depending on in which calendar year this period is applied.
Months - Representing the number of months in this period. A 1-month period cannot be converted to a period in days, because a 1-year period could be a 31-day period, a 30-day period, a 29-day period or a 28-day period depending on in which calendar month this period is applied.
Days - Representing the number of days in this period. A 1-day period cannot be converted to a duration in hours, because a 1-day period could be a 25-hour duration, a 24-hour duration, or a 23-hour duration depending on in which timezone and on which calendar date this period is applied.

The java.time.Period class does respect calendar rules and timezone rules.

Main methods offered on the java.time.Period class are:

of() - A static method returning a Period object representing the calendar period constructed with the given number of years, months and days. Note that there are no constructors in Period class. So "new Period()" is not a valid expression.
getYears() - An object method returning the years value of this Period object.
getMonths() - An object method returning the months value of this Period object.
getDays() - An object method returning the days value of this Period object.
normalized() - An object method returning a copy of this Period object with the months value normalized into the years value.
toString() - An object method returning a string representing this Period object in ISO 8601 duration format. Here is an example of toString() output, "P6Y3M1D".
plus() - An object method returns a copy of this Period object with another period added.
minus() - An object method returns a copy of this Period object with another period removed.
parse() - A static method returning a Period object representing a calendar period constructed by parsing the given character sequence using the ISO 8601 duration format of "PnYnMnD".
between() - A static method returning a Period object representing the calendar period between two given calendar dates.
addTo() - An object method returning a date-time object representing the moment of time constructed by adding this period to a given moment of time.
subtractFrom() - An object method returning a date-time object representing the moment of time constructed by subtracting this period from a given moment of time.

Table of Contents

About This JDK Tutorial Book

JDK (Java Development Kit)

►Java Date-Time API

What Is Date-Time API

java.time.Instant - Representing a Moment of Time

java.time.Instant Usage Examples

java.time.Instant - get(INSTANT_SECONDS) Error

Converting java.util.Date to java.time.Instant

java.time.ZonedDateTime - Calendar and Timezone

java.time.ZonedDateTime Usage Examples

Converting java.util.GregorianCalendar to java.time.ZonedDateTime

java.time.OffsetDateTime - Calendar and UTC Offset

java.time.OffsetDateTime Usage Examples

java.time.LocalDateTime - Local Date and time without Timezone

Partial Date and Time Objects and Classes

java.time.format.DateTimeFormatter - Date-Time Strings

java.time.Duration - Time Durations

java.time.Duration Usage Examples

►java.time.Period - Periods in Days and Months

java.time.Period Usage Examples

Date, Time and Calendar Classes

Date and Time Object and String Conversion

Number Object and Numeric String Conversion

Locales, Localization Methods and Resource Bundles

Calling and Importing Classes Defined in Unnamed Packages

HashSet, Vector, HashMap and Collection Classes

Character Set Encoding Classes and Methods

Character Set Encoding Maps

Encoding Conversion Programs for Encoded Text Files

Socket Network Communication

Datagram Network Communication

DOM (Document Object Model) - API for XML Files

SAX (Simple API for XML)

DTD (Document Type Definition) - XML Validation

XSD (XML Schema Definition) - XML Validation

XSL (Extensible Stylesheet Language)

Message Digest Algorithm Implementations in JDK

Private key and Public Key Pair Generation

PKCS#8/X.509 Private/Public Encoding Standards

Digital Signature Algorithm and Sample Program

"keytool" Commands and "keystore" Files

KeyStore and Certificate Classes

Secret Key Generation and Management

Cipher - Encryption and Decryption

The SSL (Secure Socket Layer) Protocol

SSL Socket Communication Testing Programs

SSL Client Authentication

HTTPS (Hypertext Transfer Protocol Secure)

Outdated Tutorials

Full Version in PDF/EPUB