Package com.googlecode.cqengine.attribute

Class SimpleNullableAttribute<O,A>

java.lang.Object

com.googlecode.cqengine.attribute.support.AbstractAttribute<O,A>

com.googlecode.cqengine.attribute.SimpleNullableAttribute<O,A>

All Implemented Interfaces:

Attribute<O,A>

Direct Known Subclasses:

FunctionalSimpleNullableAttribute, SimpleNullableMapAttribute

public abstract class SimpleNullableAttribute<O,A>
extends AbstractAttribute<O,A>

Represents an attribute in an object (such as a field) which can be null. Provides a method to read the value of the field given such an object.

Author:

Niall Gallagher

See Also:

SimpleAttribute

Constructor Summary

Constructors

Constructor	Description
SimpleNullableAttribute()	Creates an attribute with no name.
SimpleNullableAttribute(Class<O> objectType, Class<A> attributeType)	Creates an attribute with no name, and manually specifies the type of the attribute and its enclosing object.
SimpleNullableAttribute(Class<O> objectType, Class<A> attributeType, String attributeName)	Creates an attribute with the given name, and manually specifies the type of the attribute and its enclosing object.
SimpleNullableAttribute(String attributeName)	Creates an attribute with the given name.

Method Summary

Modifier and Type	Method	Description
abstract A	getValue(O object, QueryOptions queryOptions)	Returns the (possibly null) value of the attribute from the object.
Iterable<A>	getValues(O object, QueryOptions queryOptions)	Returns the values belonging to the attribute in the given object.

Methods inherited from class com.googlecode.cqengine.attribute.support.AbstractAttribute

calcHashCode, canEqual, equals, getAttributeName, getAttributeType, getObjectType, hashCode, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleNullableAttribute

public SimpleNullableAttribute(String attributeName)

Creates an attribute with the given name. This name is not actually used by the query engine except in providing informative exception and debug messages. As such it is recommended, but not required, that a name be provided.

A suitable name might be the name of the field to which an attribute refers.

Parameters:

attributeName - The name for this attribute

See Also:

SimpleNullableAttribute()

SimpleNullableAttribute

public SimpleNullableAttribute()

Creates an attribute with no name. A name for the attribute will be generated automatically from the name of the subclass (or anonymous class) which implements the attribute.

See Also:

SimpleNullableAttribute(String)

SimpleNullableAttribute

public SimpleNullableAttribute(Class<O> objectType,
                               Class<A> attributeType)

Creates an attribute with no name, and manually specifies the type of the attribute and its enclosing object.

Parameters:

objectType - The type of the object containing this attribute

attributeType - The type of this attribute

SimpleNullableAttribute

public SimpleNullableAttribute(Class<O> objectType,
                               Class<A> attributeType,
                               String attributeName)

Creates an attribute with the given name, and manually specifies the type of the attribute and its enclosing object.

Parameters:

objectType - The type of the object containing this attribute

attributeType - The type of this attribute

attributeName - The name for this attribute

Method Detail

getValues

public Iterable<A> getValues(O object,
                             QueryOptions queryOptions)

Returns the values belonging to the attribute in the given object.

If the attribute is a SimpleAttribute, the list returned will contain a single value for the attribute. If the attribute is a MultiValueAttribute, the list returned will contain any number of values for the attribute.

Parameters:

object - The object from which the values of the attribute are required

queryOptions - Optional parameters supplied by the application along with the operation which is causing this attribute to be invoked (either a query, or an update to the collection)

Returns:

The values for the attribute in the given object

getValue

public abstract A getValue(O object,
                           QueryOptions queryOptions)

Returns the (possibly null) value of the attribute from the object.

Parameters:

object - The object from which the value of the attribute is required

queryOptions - Optional parameters supplied by the application along with the operation which is causing this attribute to be invoked (either a query, or an update to the collection)

Returns:

The value for the attribute, which can be null