net.time4j.engine

Class ChronoEntity<T extends ChronoEntity<T>>

java.lang.Object

net.time4j.engine.ChronoEntity<T>

Type Parameters:

T - generic type of self reference

Direct Known Subclasses:

TimePoint

public abstract class ChronoEntity<T extends ChronoEntity<T>>
extends Object

Represents a temporal object which associates partial temporal values with chronological elements and also allows some manipulations of these element values.

A ChronoEntity is usually a TimePoint, where the (primary) element values determine the position on a time axis such that a time arithmetic is possible. Alternatively a ChronoEntity can also represent a partial information like the combination of month and day-of-month for a simple display of a birthday.

Chronological elements are either statically registered such that a direct access is enabled, or there is an (external) rule which enables read- and write-access. If no element rule can be found a RuleNotFoundException will be thrown.

Author:

Meno Hochschild

Constructor Summary

Constructors

Constructor and Description
ChronoEntity()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contains(ChronoElement<?> element) Queries if the value for given chronological element can be accessed via get(element).
<V> V	get(ChronoElement<V> element) Returns the partial value associated with given chronological element.
<R> R	get(ChronoFunction<? super T,R> function) Lets given query evaluate this entity.
<V> V	getMaximum(ChronoElement<V> element) Yields the maximum value of given chronological element in the current context of this entity.
<V> V	getMinimum(ChronoElement<V> element) Yields the minimum value of given chronological element in the current context of this entity.
TZID	getTimezone() Returns the associated timezone ID if available.
boolean	hasTimezone() Ermittelt, ob eine Zeitzone vorhanden ist.
boolean	isValid(ChronoElement<Integer> element, int value) Tests if the value for given chronological value is invalid.
boolean	isValid(ChronoElement<Long> element, long value) Tests if the value for given chronological value is invalid.
<V> boolean	isValid(ChronoElement<V> element, V value) Tests if the value for given chronological value is invalid.
boolean	matches(ChronoCondition<? super T> condition) Queries if this entity matches given condition.
T	with(ChronoElement<Integer> element, int value) Creates a copy of this instance with the changed element value.
T	with(ChronoElement<Long> element, long value) Creates a copy of this instance with the changed element value.
<V> T	with(ChronoElement<V> element, V value) Creates a copy of this instance with the changed element value.
T	with(ChronoOperator<T> operator) Creates a copy of this instance which is adjusted by given ChronoOperator using a strategy pattern approach.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ChronoEntity

public ChronoEntity()

Method Detail

contains

public boolean contains(ChronoElement<?> element)

Queries if the value for given chronological element can be accessed via get(element).

If the argument is missing then this method will yield false. Note: Elements which are not registered but define a suitable rule are also accessible.

Parameters:

element - chronological element to be asked (optional)

Returns:

true if the method get(ChronoElement) can be called without exception else false

See Also:

get(ChronoElement)

get

public <V> V get(ChronoElement<V> element)

Returns the partial value associated with given chronological element.

Type Parameters:

V - generic type of element value

Parameters:

element - element which has the value

Returns:

associated element value as object (never null)

Throws:

ChronoException - if the element is not registered and there is no element rule for evaluating the value

See Also:

contains(ChronoElement)

get

public final <R> R get(ChronoFunction<? super T,R> function)

Lets given query evaluate this entity.

Is equivalent to function.apply(this). The applied strategy pattern hereby enables the externalization of querying the interpretation and evaluation of this entity, consequently enabling user-defined queries with arbitrary result types R. Main difference to chronological elements is read-only access. Users have to consult the documentation of given query to decide if this method will yield null or throws an exception if the result is undefined or otherwise not obtainable.

Type Parameters:

R - generic type of result of query

Parameters:

function - time query

Returns:

result of query or null if undefined

Throws:

ChronoException - if the given query is not executable

matches

public boolean matches(ChronoCondition<? super T> condition)

Queries if this entity matches given condition.

Is equivalent to condition.test(this). This method will never throw an exception. This behaviour is in contrast to that of ChronoFunction.

Parameters:

condition - temporal condition

Returns:

true if the given condition is matched by this entity else false

See Also:

get(ChronoFunction)

isValid

public <V> boolean isValid(ChronoElement<V> element,
                  V value)

Tests if the value for given chronological value is invalid.

Notes: This method tests if given value to be in question can be set via the expression with(element, value). A numerical overflow situation (causing an ArithmeticException) will usually not be checked.

Type Parameters:

V - generic type of element value

Parameters:

element - element the given value shall be assigned to

value - candidate value to be validated (optional)

Returns:

true if the method with() can be called without exception else false

See Also:

with(ChronoElement, V)

isValid

public boolean isValid(ChronoElement<Integer> element,
              int value)

Tests if the value for given chronological value is invalid.

Notes: This method tests if given value to be in question can be set via the expression with(element, value). A numerical overflow situation (causing an ArithmeticException) will usually not be checked.

Parameters:

element - element the given value shall be assigned to

value - candidate value to be validated

Returns:

true if the method with() can be called without exception else false

See Also:

with(ChronoElement, int)

isValid

public boolean isValid(ChronoElement<Long> element,
              long value)

Tests if the value for given chronological value is invalid.

Notes: This method tests if given value to be in question can be set via the expression with(element, value). A numerical overflow situation (causing an ArithmeticException) will usually not be checked.

Parameters:

element - element the given value shall be assigned to

value - candidate value to be validated

Returns:

true if the method with() can be called without exception else false

See Also:

with(ChronoElement, long)

with

public <V> T with(ChronoElement<V> element,
         V value)

Creates a copy of this instance with the changed element value.

A null value will almost ever be seen as invalid causing an IllegalArgumentException. Subclasses which permit null must explicitly document this feature.

Type Parameters:

V - generic type of element value

Parameters:

element - chronological element

value - new element value

Returns:

changed copy of the same type, this instance remains unaffected

Throws:

ChronoException - if the element is not registered and there is no element rule for setting the value

IllegalArgumentException - if the value is not valid

ArithmeticException - in case of arithmetic overflow

See Also:

isValid(ChronoElement, V)

with

public T with(ChronoElement<Integer> element,
     int value)

Creates a copy of this instance with the changed element value.

Parameters:

element - chronological element

value - new element value

Returns:

changed copy of the same type, this instance remains unaffected

Throws:

ChronoException - if the element is not registered and there is no element rule for setting the value

IllegalArgumentException - if the value is not valid

ArithmeticException - in case of arithmetic overflow

See Also:

isValid(ChronoElement, V)

with

public T with(ChronoElement<Long> element,
     long value)

Creates a copy of this instance with the changed element value.

Parameters:

element - chronological element

value - new element value

Returns:

changed copy of the same type, this instance remains unaffected

Throws:

ChronoException - if the element is not registered and there is no element rule for setting the value

IllegalArgumentException - if the value is not valid

ArithmeticException - in case of arithmetic overflow

See Also:

isValid(ChronoElement, V)

with

public T with(ChronoOperator<T> operator)

Creates a copy of this instance which is adjusted by given ChronoOperator using a strategy pattern approach.

Is equivalent to operator.apply(this). Hereby a user-defined manipulation will be externalized and is semantically similar to the reading counterpart ChronoFunction.

Parameters:

operator - operator for adjusting the element values

Returns:

changed copy of the same type, this instance remains unaffected

Throws:

ChronoException - if no element rule exists for setting the values

IllegalArgumentException - if any new value is not valid

ArithmeticException - in case of arithmetic overflow

See Also:

get(ChronoFunction)

getMinimum

public <V> V getMinimum(ChronoElement<V> element)

Yields the minimum value of given chronological element in the current context of this entity.

The definition of a minimum and a maximum does generally not imply that every intermediate value between minimum and maximum is valid in this context. For example in the timezone Europe/Berlin the hour [T02:00] will be invalid if switching to summer time.

In most cases the minimum value is not dependent on this context.

Type Parameters:

V - generic type of element value

Parameters:

element - element whose minimum value is to be evaluated

Returns:

minimum maybe context-dependent element value

Throws:

ChronoException - if the element is not registered and there is no element rule for getting the minimum value

See Also:

ChronoElement.getDefaultMinimum(), getMaximum(ChronoElement)

getMaximum

public <V> V getMaximum(ChronoElement<V> element)

Yields the maximum value of given chronological element in the current context of this entity.

Maximum values are different from minimum case often dependent on the context. An example is the element SECOND_OF_MINUTE whose maximum is normally 59 but can differ in UTC-context with leap seconds. Another more common example is the maximum of the element DAY_OF_MONTH (28-31) which is dependent on the month and year of this context/entity (leap years!).

Note: In timezone-related timestamps possible offset jumps inducing gaps on the local timeline will be conserved. That means that minimum and maximum do not guarantee a continuum of valid intermediate values.

Type Parameters:

V - generic type of element value

Parameters:

element - element whose maximum value is to be evaluated

Returns:

maximum maybe context-dependent element value

Throws:

ChronoException - if the element is not registered and there is no element rule for getting the maximum value

See Also:

ChronoElement.getDefaultMaximum(), getMinimum(ChronoElement)

hasTimezone

public boolean hasTimezone()

Ermittelt, ob eine Zeitzone vorhanden ist.

Diese Implementierung kennt standardmäßig keine Zeitzone und liefert false. Subklassen mit Zeitzonenbezug werden die Methode in geeigneter Weise überschreiben.

Returns:

true if a timezone is available and can be achieved with getTimezone() else false

getTimezone

public TZID getTimezone()

Returns the associated timezone ID if available.

This implementation throws a ChronoException by default. Subclasses with timezone reference will override the method in a suitable way.

Returns:

timezone identifier if available

Throws:

ChronoException - if the timezone is not available

See Also:

hasTimezone()