org.dasein.attributes
Class DataType<V>

java.lang.Object
  org.dasein.attributes.DataType<V>

Type Parameters:

V - the Java data type that this data type operates on

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

BooleanFactory.BooleanAttribute, CurrencyFactory.CurrencyAttribute, DateFactory.DateAttribute, DecimalFactory.DecimalAttribute, NameValuePairFactory.NameValuePairAttribute, NumberFactory.NumberAttribute, StringFactory.StringAttribute, TimeFactory.DateAttribute

public abstract class DataType<V>
extends Object
implements Serializable

Represents a data type for the Dasein attributes system. A data type governs what kind of values are valid for any attribute having this data type. To create custom data types, you must extend this class as well as the DataTypeFactory class.

Last modified: $Date: 2009/02/02 19:27:05 $

Version:

$Revision: 1.7 $

Author:

George Reese

See Also:

Serialized Form

Nested Class Summary

static class

DataType.InputType Represents a type of input field associated with inputting values associated with this attributes system.

Constructor Summary

DataType(String nom, String grp, Number idx, boolean ml, boolean mv, boolean req, String... params)
Constructs a new data type instance.

Method Summary

boolean	equals(Object ob) Two data type instances are considered identical if everything about them is the same.
abstract Collection<V>	getChoices() Provides a list of values considered valid for this data type.
abstract DataTypeFactory<V>	getFactory()
String	getGroup()
int	getIndex()
abstract DataType.InputType	getInputType()
String	getName()
Collection<String>	getParameters() Type parameters tell a data type how to constrain values.
int	getSize()
Translator<V>	getTranslatedValue(Object src, Locale loc, Translator<?> curr) Provides a Translator instance for the requested value.
abstract V	getValue(Object src) Implementors will implement this method to convert a raw value into a valid value of this data type.
Collection<V>	getValues(Object src) When a data type is multi-valued, this method is called to convert raw data into a collection of values matching this data type.
int	hashCode()
boolean	isMultiLingual()
boolean	isMultiValued()
boolean	isRequired()
abstract boolean	isValidChoice(V arg) Checks the specified value to see if it is valid for this data type.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

DataType

public DataType(String nom,
                String grp,
                Number idx,
                boolean ml,
                boolean mv,
                boolean req,
                String... params)

Constructs a new data type instance. Implementations will generally override this with custom constructors that do something meaningful with the type parameters.

Parameters:

nom - the name of the data type

grp - the group of the data type

idx - the index of the data type

ml - true if the type is multi-lingual

mv - true if the type allows more than one value

req - true if the type requires a value (cannot be null)

params - a list of parameters constraining this type

Method Detail

equals

public boolean equals(Object ob)

Two data type instances are considered identical if everything about them is the same.

Overrides:

equals in class Object

Returns:

true if both data type instances represent the same exact data type

getChoices

public abstract Collection<V> getChoices()

Provides a list of values considered valid for this data type. If any object of the type governed by this data type is allowed, this method will return null.

Returns:

a list of allowed values or null to allow any value

getFactory

public abstract DataTypeFactory<V> getFactory()

Returns:

the factory object that owns this data type

getInputType

public abstract DataType.InputType getInputType()

Returns:

the type of input that a user interface should provide to prompt a user for a value

getName

public final String getName()

Returns:

the name of this data type

getGroup

public final String getGroup()

Returns:

the group of this data type

getIndex

public final int getIndex()

Returns:

the index of this data type

getParameters

public final Collection<String> getParameters()

Type parameters tell a data type how to constrain values. What these parameters are and how they are interpreted are left entirely up to the implementing classes.

Returns:

the constraining parameters for this data type

getSize

public int getSize()

Returns:

the recommended size for an input field

getTranslatedValue

public Translator<V> getTranslatedValue(Object src,
                                        Locale loc,
                                        Translator<?> curr)

Provides a Translator instance for the requested value. This method is generally called to turn an arbitrary object into a multi-lingual instance of of the variable. Basically, when the system is trying to convert arbitrary data—such as user input or values from a persistence engine—into proper values for this type, it will call either this method or getValue(Object). Which method is called is dependent on whether this data type is multi-lingual. If the data type is multi-lingual, this method is called. This method will, in turn, call getValue(Object) and wrap it in a Translator.

Parameters:

src - the raw data to be converted

loc - the locale associated with this value

curr - any current values for other languages

Returns:

a combined multi-lingual value

getValue

public abstract V getValue(Object src)

Implementors will implement this method to convert a raw value into a valid value of this data type. Implementations should throw an InvalidAttributeException if they are unable to interpret the raw value.

Parameters:

src - the raw value, such as user input or a string from a persistent store

Returns:

a converted value of this data type

getValues

public Collection<V> getValues(Object src)

When a data type is multi-valued, this method is called to convert raw data into a collection of values matching this data type. If the raw value is a string, this method assumes that the string represents a comma-delimited, multi-value attribute.

Parameters:

src - the raw source value

Returns:

the converted value

hashCode

public int hashCode()

Overrides:

hashCode in class Object

Returns:

a unique hash code for this instance of this class

isMultiLingual

public final boolean isMultiLingual()

Returns:

true if this data type supports multiple values for different languages

isMultiValued

public final boolean isMultiValued()

Returns:

true if this data type allows for multiple values

isRequired

public final boolean isRequired()

Returns:

true if this data type must have a value (cannot be null)

isValidChoice

public abstract boolean isValidChoice(V arg)

Checks the specified value to see if it is valid for this data type. In general, implementing classes will check the following:

• that the value is not required in the instance of a null value
• that the value is a member of the choices provided by getChoices()
• any other criteria an implementor might want to validate

Parameters:

arg - the value being validated

Returns:

true if the value is valid for this data type

toString

public String toString()

Overrides:

toString in class Object

Returns:

a string representation of this data type