net.time4j.engine

Class BasicElement<V>

java.lang.Object

net.time4j.engine.BasicElement<V>

Type Parameters:

V - generic type of element values

All Implemented Interfaces:

Serializable, Comparator<ChronoDisplay>, ChronoElement<V>

Direct Known Subclasses:

AdvancedElement

public abstract class BasicElement<V>
extends Object
implements ChronoElement<V>, Serializable

Abstract base implementation of a chronological element which has a name and can also define an (unregistered) element rule.

Author:

Meno Hochschild

See Also:

Serialized Form

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BasicElement(String name) Called by subclasses which will usually assign an instance to a static constant (creating a singleton).

Method Summary

Methods

Modifier and Type	Method and Description
protected <T extends ChronoEntity<T>> ElementRule<T,V>	derive(Chronology<T> chronology) Derives an optional element rule for given chronology.
boolean	equals(Object obj) Based on equality of element names AND element classes.
protected ChronoElement<?>	getParent() Points to another element which can have a base unit in a given chronology.
char	getSymbol() There is no format symbol by default.
protected String	getVeto(Chronology<?> chronology) If this element is not registered in given chronology then this method will be called by Time4J in order to generate a suitable error message in cases where this element shall not support the chronological context.
int	hashCode() Based on the element name.
boolean	isLenient() Chronological elements are strict by default.
boolean	isLocal() Elements are local by default and can therefore not be used in a global context.
String	name() Returns the name which is unique within the context of a given chronology.
String	toString() Serves mainly for debugging support.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.time4j.engine.ChronoElement

compare, getDefaultMaximum, getDefaultMinimum, getType, isDateElement, isTimeElement

Constructor Detail

BasicElement

protected BasicElement(String name)

Called by subclasses which will usually assign an instance to a static constant (creating a singleton).

Parameters:

name - name of element

Throws:

IllegalArgumentException - if the name is empty or only contains white space (spaces, tabs etc.)

See Also:

ChronoElement.name()

Method Detail

name

public final String name()

Description copied from interface: ChronoElement

Returns the name which is unique within the context of a given chronology.

The name can also serve as resource key together with the name of a chronology for a localized description.

Specified by:

name in interface ChronoElement<V>

Returns:

name of element, unique within a chronology

getSymbol

public char getSymbol()

There is no format symbol by default.

In order to define a format symbol subclasses must override this methode. In that case such an element instance should be annotated with the annotation FormattableElement for documentation support.

Specified by:

getSymbol in interface ChronoElement<V>

Returns:

ASCII-0 (placeholder for an undefined format symbol)

See Also:

FormattableElement

isLenient

public boolean isLenient()

Chronological elements are strict by default.

Specified by:

isLenient in interface ChronoElement<V>

Returns:

false

See Also:

ElementRule.withValue(T, V, boolean)

isLocal

public boolean isLocal()

Elements are local by default and can therefore not be used in a global context.

Returns:

true

Since:

2.0

See Also:

getVeto(Chronology)

equals

public boolean equals(Object obj)

Based on equality of element names AND element classes.

Specified by:

equals in interface Comparator<ChronoDisplay>

Overrides:

equals in class Object

Returns:

true if this instance and the argument are of same class and have same names else false

hashCode

public int hashCode()

Based on the element name.

Overrides:

hashCode in class Object

Returns:

int

toString

public String toString()

Serves mainly for debugging support.

For display purpose the method name() is to be preferred.

Overrides:

toString in class Object

Returns:

String

derive

protected <T extends ChronoEntity<T>> ElementRule<T,V> derive(Chronology<T> chronology)

Derives an optional element rule for given chronology.

Note: This implementation yields null. Subclasses whose element instances are not registered in a given chronology must override this method returning a suitable element rule.

Type Parameters:

T - generic type of chronology

Parameters:

chronology - chronology an element rule is searched for

Returns:

element rule or null if given chronology is unsupported

getParent

protected ChronoElement<?> getParent()

Points to another element which can have a base unit in a given chronology.

This method can be overridden by unregistered extension elements in order to help a chronology to see which base unit belongs to this element.

Returns:

parent element registered on a time axis for helping retrieving a base unit for this element or null

See Also:

TimeAxis.getBaseUnit(ChronoElement)

getVeto

protected String getVeto(Chronology<?> chronology)

If this element is not registered in given chronology then this method will be called by Time4J in order to generate a suitable error message in cases where this element shall not support the chronological context.

This implementation yields null to indicate that there is no veto against usage in given chronology unless this element is local but the given chronology is global.

Parameters:

chronology - chronological context

Returns:

error message as veto or null

Since:

2.0