javax.time
Class Instant

java.lang.Object
  extended by javax.time.Instant
All Implemented Interfaces:
java.io.Serializable, java.lang.Comparable<Instant>, InstantProvider

public final class Instant
extends java.lang.Object
implements InstantProvider, java.lang.Comparable<Instant>, java.io.Serializable

An instantaneous point on the time-line.

The Time Framework for Java models time as a series of instantaneous events, known as instants, along a single time-line. This class represents one of those instants.

An instant is in reality an instantaneous event on an infinite time-line. However, for practicality this API uses a precision of nanoseconds. In addition, this API limits the measurable time-line to the number of seconds that can be held in a long. This is greater than the current estimated age of the universe.

In order to represent the data a 96 bit number is required. To achieve this the data is stored as seconds, measured using a long, and nanoseconds, measured using an int. The nanosecond part will always be between 0 and 999,999,999 representing the nanosecond part of the second.

The seconds are measured from the standard Java epoch of 1970-01-01T00:00:00Z. Instants on the time-line after the epoch are positive, earlier are negative.

Time-scale

Instant uses the UTC-SLS time-scale which always has 86400 seconds in a day. Essentially, UTC-SLS is a consistent mechanism of converting an accurate UTC time (potentially with leap seconds) to a 86400 second day. Its main benefit is that in an accurate implementation, the UTC-SLS time never experiences any gaps or overlaps.

UTC-SLS is defined as spreading any leap second evenly over the last 1000 seconds of the day. This corresponds to times after 23:43:21 on a day with an added leap second, or times after 23:43:19 on a day with a removed leap second.

The UTC-SLS conversion only matters to users of this class with high precision requirements. To keep full track of an instant using an accurate time-scale use the UTCInstant or TAIInstant class. For most applications, the behavior where each day has exactly 84000 seconds is the desired one. The UTC-SLS time-scale is also used for all human-scale date-time classes, such as OffsetDateTime and ZonedDateTime.

The standard Java epoch of 1970 is prior to the introduction of whole leap seconds into UTC in 1972. As such, the Time Framework for Java needs to define what the 1970 epoch actually means. The chosen definition is that there are no leap seconds or rate changes in the Java version of UTC prior to 1972, thus it remains 10 seconds offset from TAI. This differs from an accurate UTC implementation, but is relatively easy to handle if accuracy is required.

Operations to add or subtract durations will ignore leap seconds. Use UTCInstant or TAIInstant if accurate duration calculations are required.

Instant is immutable and thread-safe.

Author:
Michael Nascimento Santos, Stephen Colebourne
See Also:
Serialized Form

Field Summary
static Instant EPOCH
          Constant for the 1970-01-01T00:00:00Z epoch instant.
 
Method Summary
 int compareTo(Instant otherInstant)
          Compares this instant to the specified instant.
 boolean equals(java.lang.Object otherInstant)
          Checks if this instant is equal to the specified instant.
 long getEpochSeconds()
          Gets the number of seconds from the Java epoch of 1970-01-01T00:00:00Z.
 int getNanoOfSecond()
          Gets the number of nanoseconds, later along the time-line, from the start of the second.
 int hashCode()
          Returns a hash code for this instant.
 boolean isAfter(Instant otherInstant)
          Checks if this instant is after the specified instant.
 boolean isBefore(Instant otherInstant)
          Checks if this instant is before the specified instant.
 Instant minus(Duration duration)
          Returns a copy of this instant with the specified duration subtracted.
 Instant minus(long amount, java.util.concurrent.TimeUnit unit)
          Returns a copy of this duration with the specified duration subtracted.
 Instant minusMillis(long millisToSubtract)
          Returns a copy of this instant with the specified duration in milliseconds subtracted.
 Instant minusNanos(long nanosToSubtract)
          Returns a copy of this instant with the specified duration in nanoseconds subtracted.
 Instant minusSeconds(long secondsToSubtract)
          Returns a copy of this instant with the specified duration in seconds subtracted.
static Instant now()
          Obtains the current instant from the system time-source in the default time-zone.
static Instant now(TimeSource timeSource)
          Obtains the current instant from the specified clock.
static Instant of(InstantProvider instantProvider)
          Obtains an instance of Instant from a provider of instants.
static Instant ofEpochMillis(long epochMillis)
          Obtains an instance of Instant using milliseconds from the epoch of 1970-01-01T00:00:00Z.
static Instant ofEpochNanos(java.math.BigInteger epochNanos)
          Obtains an instance of Instant using nanoseconds from the epoch of 1970-01-01T00:00:00Z.
static Instant ofEpochNanos(long epochNanos)
          Obtains an instance of Instant using nanoseconds from the epoch of 1970-01-01T00:00:00Z.
static Instant ofEpochSeconds(java.math.BigDecimal epochSeconds)
          Obtains an instance of Instant using seconds from the epoch of 1970-01-01T00:00:00Z.
static Instant ofEpochSeconds(long epochSeconds)
          Obtains an instance of Instant using seconds from the epoch of 1970-01-01T00:00:00Z.
static Instant ofEpochSeconds(long epochSeconds, long nanoAdjustment)
          Obtains an instance of Instant using seconds from the epoch of 1970-01-01T00:00:00Z and nanosecond fraction of second.
static Instant parse(java.lang.String text)
          Obtains an instance of Instant by parsing a string.
 Instant plus(Duration duration)
          Returns a copy of this instant with the specified duration added.
 Instant plus(long amount, java.util.concurrent.TimeUnit unit)
          Returns a copy of this duration with the specified duration added.
 Instant plusMillis(long millisToAdd)
          Returns a copy of this instant with the specified duration in milliseconds added.
 Instant plusNanos(long nanosToAdd)
          Returns a copy of this instant with the specified duration in nanoseconds added.
 Instant plusSeconds(long secondsToAdd)
          Returns a copy of this instant with the specified duration in seconds added.
 long toEpochMillisLong()
          Converts this instant to the number of milliseconds from the epoch of 1970-01-01T00:00:00Z.
 java.math.BigInteger toEpochNanos()
          Converts this instant to the number of nanoseconds from the epoch of 1970-01-01T00:00:00Z expressed as a BigInteger.
 java.math.BigDecimal toEpochSeconds()
          Converts this instant to the number of seconds from the epoch of 1970-01-01T00:00:00Z expressed as a BigDecimal.
 Instant toInstant()
          Converts this instant to an Instant, trivially returning this.
 java.lang.String toString()
          A string representation of this instant using ISO-8601 representation.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

EPOCH

public static final Instant EPOCH
Constant for the 1970-01-01T00:00:00Z epoch instant.

Method Detail

now

public static Instant now()
Obtains the current instant from the system time-source in the default time-zone.

This will query the system time-source to obtain the current instant.

Using this method will prevent the ability to use an alternate time-source for testing because the time-source is hard-coded.

Returns:
the current instant using the system clock, never null

now

public static Instant now(TimeSource timeSource)
Obtains the current instant from the specified clock.

This will query the specified time-source to obtain the current time.

Using this method allows the use of an alternate clock for testing. The alternate clock may be introduced using dependency injection.

Parameters:
timeSource - the time-source to use, not null
Returns:
the current instant, never null

ofEpochSeconds

public static Instant ofEpochSeconds(long epochSeconds)
Obtains an instance of Instant using seconds from the epoch of 1970-01-01T00:00:00Z.

The nanosecond field is set to zero.

Parameters:
epochSeconds - the number of seconds from the epoch of 1970-01-01T00:00:00Z
Returns:
an instant, never null

ofEpochSeconds

public static Instant ofEpochSeconds(long epochSeconds,
                                     long nanoAdjustment)
Obtains an instance of Instant using seconds from the epoch of 1970-01-01T00:00:00Z and nanosecond fraction of second.

This method allows an arbitrary number of nanoseconds to be passed in. The factory will alter the values of the second and nanosecond in order to ensure that the stored nanosecond is in the range 0 to 999,999,999. For example, the following will result in the exactly the same instant:

  Instant.ofSeconds(3, 1);
  Instant.ofSeconds(4, -999999999);
  Instant.ofSeconds(2, 1000000001);
 

Parameters:
epochSeconds - the number of seconds from the epoch of 1970-01-01T00:00:00Z
nanoAdjustment - the nanosecond adjustment to the number of seconds, positive or negative
Returns:
an instant, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

ofEpochSeconds

public static Instant ofEpochSeconds(java.math.BigDecimal epochSeconds)
Obtains an instance of Instant using seconds from the epoch of 1970-01-01T00:00:00Z.

The seconds and nanoseconds are extracted from the specified BigDecimal. If the decimal is larger than Long.MAX_VALUE or has more than 9 decimal places then an exception is thrown.

Parameters:
epochSeconds - the number of seconds, up to scale 9
Returns:
an instant, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

ofEpochMillis

public static Instant ofEpochMillis(long epochMillis)
Obtains an instance of Instant using milliseconds from the epoch of 1970-01-01T00:00:00Z.

The seconds and nanoseconds are extracted from the specified milliseconds.

Parameters:
epochMillis - the number of milliseconds
Returns:
an instant, never null

ofEpochNanos

public static Instant ofEpochNanos(long epochNanos)
Obtains an instance of Instant using nanoseconds from the epoch of 1970-01-01T00:00:00Z.

The seconds and nanoseconds are extracted from the specified nanoseconds.

Parameters:
epochNanos - the number of nanoseconds
Returns:
an instant, never null

ofEpochNanos

public static Instant ofEpochNanos(java.math.BigInteger epochNanos)
Obtains an instance of Instant using nanoseconds from the epoch of 1970-01-01T00:00:00Z.

The seconds and nanoseconds are extracted from the specified BigInteger. If the resulting seconds value is larger than Long.MAX_VALUE then an exception is thrown.

Parameters:
epochNanos - the number of nanoseconds, not null
Returns:
an instant, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

of

public static Instant of(InstantProvider instantProvider)
Obtains an instance of Instant from a provider of instants.

In addition to calling InstantProvider.toInstant() this method also checks the validity of the result of the provider.

Parameters:
instantProvider - a provider of instant information, not null
Returns:
an instant, never null

parse

public static Instant parse(java.lang.String text)
Obtains an instance of Instant by parsing a string.

This will parse the string produced by toString() which is the ISO-8601 format yyyy-MM-ddTHH:mm:ss.SSSSSSSSSZ. The numbers must be ASCII numerals. The seconds are mandatory, but the fractional seconds are optional. There must be no more than 9 digits after the decimal point. The letters (T and Z) will be accepted in upper or lower case. The decimal point may be either a dot or a comma.

Parameters:
text - the text to parse, not null
Returns:
an instant, never null
Throws:
CalendricalParseException - if the text cannot be parsed to an Instant

getEpochSeconds

public long getEpochSeconds()
Gets the number of seconds from the Java epoch of 1970-01-01T00:00:00Z.

The epoch second count is a simple incrementing count of seconds where second 0 is 1970-01-01T00:00:00Z. The nanosecond part of the day is returned by getNanosOfSecond.

Returns:
the seconds from the epoch of 1970-01-01T00:00:00Z

getNanoOfSecond

public int getNanoOfSecond()
Gets the number of nanoseconds, later along the time-line, from the start of the second.

The nanosecond-of-second value measures the total number of nanoseconds from the second returned by getEpochSeconds.

Returns:
the nanoseconds within the second, always positive, never exceeds 999,999,999

plus

public Instant plus(Duration duration)
Returns a copy of this instant with the specified duration added.

This instance is immutable and unaffected by this method call.

Parameters:
duration - the duration to add, positive or negative, not null
Returns:
an Instant based on this instant with the specified duration added, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

plus

public Instant plus(long amount,
                    java.util.concurrent.TimeUnit unit)
Returns a copy of this duration with the specified duration added.

The duration to be added is measured in terms of the specified unit.

This instance is immutable and unaffected by this method call.

Parameters:
amount - the duration to add, positive or negative
unit - the unit that the duration is measured in, not null
Returns:
an Instant based on this duration with the specified duration added, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

plusSeconds

public Instant plusSeconds(long secondsToAdd)
Returns a copy of this instant with the specified duration in seconds added.

This instance is immutable and unaffected by this method call.

Parameters:
secondsToAdd - the seconds to add, positive or negative
Returns:
an Instant based on this instant with the specified seconds added, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

plusMillis

public Instant plusMillis(long millisToAdd)
Returns a copy of this instant with the specified duration in milliseconds added.

This instance is immutable and unaffected by this method call.

Parameters:
millisToAdd - the milliseconds to add, positive or negative
Returns:
an Instant based on this instant with the specified milliseconds added, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

plusNanos

public Instant plusNanos(long nanosToAdd)
Returns a copy of this instant with the specified duration in nanoseconds added.

This instance is immutable and unaffected by this method call.

Parameters:
nanosToAdd - the nanoseconds to add, positive or negative
Returns:
an Instant based on this instant with the specified nanoseconds added, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

minus

public Instant minus(Duration duration)
Returns a copy of this instant with the specified duration subtracted.

This instance is immutable and unaffected by this method call.

Parameters:
duration - the duration to subtract, positive or negative, not null
Returns:
an Instant based on this instant with the specified duration subtracted, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

minus

public Instant minus(long amount,
                     java.util.concurrent.TimeUnit unit)
Returns a copy of this duration with the specified duration subtracted.

The duration to be subtracted is measured in terms of the specified unit.

This instance is immutable and unaffected by this method call.

Parameters:
amount - the duration to subtract, positive or negative
unit - the unit that the duration is measured in, not null
Returns:
a Duration based on this duration with the specified duration subtracted, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

minusSeconds

public Instant minusSeconds(long secondsToSubtract)
Returns a copy of this instant with the specified duration in seconds subtracted.

This instance is immutable and unaffected by this method call.

Parameters:
secondsToSubtract - the seconds to subtract, positive or negative
Returns:
an Instant based on this instant with the specified seconds subtracted, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

minusMillis

public Instant minusMillis(long millisToSubtract)
Returns a copy of this instant with the specified duration in milliseconds subtracted.

This instance is immutable and unaffected by this method call.

Parameters:
millisToSubtract - the milliseconds to subtract, positive or negative
Returns:
an Instant based on this instant with the specified milliseconds subtracted, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

minusNanos

public Instant minusNanos(long nanosToSubtract)
Returns a copy of this instant with the specified duration in nanoseconds subtracted.

This instance is immutable and unaffected by this method call.

Parameters:
nanosToSubtract - the nanoseconds to subtract, positive or negative
Returns:
an Instant based on this instant with the specified nanoseconds subtracted, never null
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

toEpochSeconds

public java.math.BigDecimal toEpochSeconds()
Converts this instant to the number of seconds from the epoch of 1970-01-01T00:00:00Z expressed as a BigDecimal.

Returns:
the number of seconds since the epoch of 1970-01-01T00:00:00Z, scale 9, never null

toEpochNanos

public java.math.BigInteger toEpochNanos()
Converts this instant to the number of nanoseconds from the epoch of 1970-01-01T00:00:00Z expressed as a BigInteger.

Returns:
the number of nanoseconds since the epoch of 1970-01-01T00:00:00Z, never null

toEpochMillisLong

public long toEpochMillisLong()
Converts this instant to the number of milliseconds from the epoch of 1970-01-01T00:00:00Z.

If this instant represents a point on the time-line too far in the future or past to fit in a long milliseconds, then an exception is thrown.

If this instant has greater than millisecond precision, then the conversion will drop any excess precision information as though the amount in nanoseconds was subject to integer division by one million.

Returns:
the number of milliseconds since the epoch of 1970-01-01T00:00:00Z
Throws:
java.lang.ArithmeticException - if the calculation exceeds the supported range

toInstant

public Instant toInstant()
Converts this instant to an Instant, trivially returning this.

Specified by:
toInstant in interface InstantProvider
Returns:
this, never null

compareTo

public int compareTo(Instant otherInstant)
Compares this instant to the specified instant.

The comparison is based on the time-line position of the instants.

Specified by:
compareTo in interface java.lang.Comparable<Instant>
Parameters:
otherInstant - the other instant to compare to, not null
Returns:
the comparator value, negative if less, positive if greater
Throws:
java.lang.NullPointerException - if otherInstant is null

isAfter

public boolean isAfter(Instant otherInstant)
Checks if this instant is after the specified instant.

The comparison is based on the time-line position of the instants.

Parameters:
otherInstant - the other instant to compare to, not null
Returns:
true if this instant is after the specified instant
Throws:
java.lang.NullPointerException - if otherInstant is null

isBefore

public boolean isBefore(Instant otherInstant)
Checks if this instant is before the specified instant.

The comparison is based on the time-line position of the instants.

Parameters:
otherInstant - the other instant to compare to, not null
Returns:
true if this instant is before the specified instant
Throws:
java.lang.NullPointerException - if otherInstant is null

equals

public boolean equals(java.lang.Object otherInstant)
Checks if this instant is equal to the specified instant.

The comparison is based on the time-line position of the instants.

Overrides:
equals in class java.lang.Object
Parameters:
otherInstant - the other instant, null returns false
Returns:
true if the other instant is equal to this one

hashCode

public int hashCode()
Returns a hash code for this instant.

Overrides:
hashCode in class java.lang.Object
Returns:
a suitable hash code

toString

public java.lang.String toString()
A string representation of this instant using ISO-8601 representation.

The format of the returned string will be yyyy-MM-ddTHH:mm:ss.SSSSSSSSSZ.

Overrides:
toString in class java.lang.Object
Returns:
an ISO-8601 representation of this instant, never null