de.tmasoft.acaf.base

Class Attribute<A extends AttributeInterface<?>>

java.lang.Object

de.tmasoft.acaf.base.Attribute<A>

All Implemented Interfaces:

AttributeInterface<A>

Direct Known Subclasses:

ComponentContainerBase, ComponentReferenceBase, DateTimeBaseAttribute, DoubleAttribute, DurationAttribute, EnumAttribute, FloatAttribute, IntegerAttribute, LongAttribute, SetAttribute, StringAttribute

public abstract class Attribute<A extends AttributeInterface<?>>
extends java.lang.Object
implements AttributeInterface<A>

This class implements the attribute interface. It serves as abstract base class for all concrete attributes of the component framework. It plays the role of the leaf in the composite design pattern, the subject in the observer design pattern and the element in the visitor design pattern.

The attribute is contained in the attribute list of a component (composite). It has an unique keyword inside a component.

Observer objects (AttributeObserver) can be attached to the attribute if they want to be notified about a value change of the attribute. The notification is initiated by the concrete derived attributes calling the method notifyObservers(). Observers can be removed from the observer list while they are notified.

See Also:

ComponentInterface

Field Summary

Fields

Modifier and Type	Field and Description
protected AttributeValueFormatInterface<? super A>	formatter The attribute value formatter used by the method formatValue().
protected MessageCatalogInterface	messageCatalog The message catalog used to get the display keyword.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Attribute(java.lang.String keyword, java.lang.Object displayKeywordKey, MessageCatalogInterface messageCatalog, java.lang.String attributeType, boolean readonly) The constructor initializes the attribute with the passed parameters.

Method Summary

Modifier and Type	Method and Description
void	acceptVisitor(Visitor visitor) This method applies to the visitor pattern and accepts a visitor for the attribute.
void	attachObserver(AttributeObserver<? super A> observer) This method applies to the observer design pattern and attaches the observer to the attribute.
void	clear() This method resets the value of the attribute to its default value.
void	copyValue(A sourceAttribute, ComponentInterface<?> component) This method implements the interface AttributeInterface and copies the value of the passed source attribute to this attribute.
void	detachObserver(AttributeObserver<? super A> observer) This method removes the observer from the attribute (see also attachObserver(AttributeObserver)).
java.lang.String	formatValue() This method returns the value of the attribute as string in user friendly formatted way.
java.lang.String	getDisplayKeyword() This method returns the display keyword of the attribute.
java.lang.String	getDisplayKeyword(java.util.Locale locale) This method returns the display keyword of the attribute in the passed locale.
java.lang.String	getKeyword() This method returns the keyword of the attribute.
AttributeMode	getMode() This method returns the mode of the attribute.
java.lang.String	getType() This method returns the type of the attribute as string.
java.lang.String	getTypeInfo() This method returns the attribute type, the mode character and the value information in one string separated by comma.
java.lang.String	getValueAsString() This method returns the string representation of the attribute value.
java.lang.String	getValueInfo() This method returns the valid values for the attribute.
boolean	isReadonly() This method returns true if the attribute mode is AttributeMode.READ_ONLY, otherwise false.
boolean	isValueEqual(A otherAttribute) This method implements the interface AttributeInterface and compares the value of the passed attribute with the value of this attribute.
protected void	notifyObservers() This method notifies all observer objects about the attribute value change.
void	setAttributeValueFormatter(AttributeValueFormatInterface<? super A> formatter) This method can be used to set a custom value formatter.
void	setValueWithString(java.lang.String newValue) This method converts the passed string representation of the attribute value to the specific attribute value.

Methods inherited from class java.lang.Object

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

Field Detail

messageCatalog

protected MessageCatalogInterface messageCatalog

The message catalog used to get the display keyword.

formatter

protected AttributeValueFormatInterface<? super A extends AttributeInterface<?>> formatter

The attribute value formatter used by the method formatValue().

Constructor Detail

Attribute

protected Attribute(java.lang.String keyword,
                    java.lang.Object displayKeywordKey,
                    MessageCatalogInterface messageCatalog,
                    java.lang.String attributeType,
                    boolean readonly)

The constructor initializes the attribute with the passed parameters. The keyword identifies the attribute in its parent component. The display keyword should be a locale specific string, which is used to identify the attribute at a user interface (i.e. GUI). The display keyword is used by the framework in attribute specific exception messages. If null is passed for the display keyword, the keyword is used as display keyword. The attribute type is a string which describes the type of the attribute. The framework uses the attribute type strings defined by the class AttributeTypeTable in this package. The readonly parameter determines if the attribute mode is set to AttributeMode.READ_WRITE or AttributeMode.READ_WRITE. The mode is usually used to determine if the attribute can be modified by the user or only internally by the application. The attribute classes itself do not check the mode. This is the responsibility of the caller.

Parameters:

keyword - The keyword of the attribute, used to identify the attribute in its owning component.

displayKeywordKey - The key of the display keyword in the message catalog. The display keyword is a locale specific text used to identify the attribute in error messages and user interfaces. If null is passed, the keyword is used as display keyword instead.

messageCatalog - The message catalog used to get the display keyword. If null is passed, the keyword is used as display keyword instead.

attributeType - The attribute type as string describing the type of the concrete attribute.

readonly - The attribute mode. If true is passed the attribute mode AttributeMode.READ_ONLY is set, otherwise AttributeMode.READ_WRITE. The flag determines if the attribute is modifiable by the user (false) or not (true).

Method Detail

acceptVisitor

public void acceptVisitor(Visitor visitor)
                   throws AcafException

This method applies to the visitor pattern and accepts a visitor for the attribute. The implementation calls the method Visitor.visitAttribute(AttributeInterface) of the passed visitor.

Specified by:

acceptVisitor in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

visitor - The visitor.

Throws:

AcafException - May be thrown by the visitor.

attachObserver

public void attachObserver(AttributeObserver<? super A> observer)

This method applies to the observer design pattern and attaches the observer to the attribute. The observer is informed about the value change of the attribute. The observers are inserted in a double linked list. One observer can be attached more than once. It has to be detached (see method detachObserver(AttributeObserver)) as often as it has been attached. Observers are prepended to the list and notified in the reverse order as they are attached. This gives the user the possibility to attach new observers while the notification is in progress. If observers are attached while the notification is in progress these observers are not notified!

Specified by:

attachObserver in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

observer - The observer to attached to the attribute.

clear

public void clear()
           throws AttributeException

This method resets the value of the attribute to its default value.

This implementation here is empty.

Specified by:

clear in interface AttributeInterface<A extends AttributeInterface<?>>

Throws:

AttributeException - May be thrown by implementing classes, when setting the default value fails.

copyValue

public void copyValue(A sourceAttribute,
                      ComponentInterface<?> component)
               throws AcafException

This method implements the interface AttributeInterface and copies the value of the passed source attribute to this attribute. This implementation calls the method setValueWithString(String) with the value returned by getValueAsString() of the source attribute.

Specified by:

copyValue in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

sourceAttribute - The source attribute, the value is copied from.

component - The parent component containing this attribute. The component is not used here.

Throws:

AcafException - Thrown, when copying the attribute value fails.

See Also:

ComponentInterface.createCopy(ComponentInterface), Component.addAttribute(AttributeInterface)

detachObserver

public void detachObserver(AttributeObserver<? super A> observer)

This method removes the observer from the attribute (see also attachObserver(AttributeObserver)). The observer must implement the method Object.equals(Object) to be removed properly.

Specified by:

detachObserver in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

observer - The observer to be detached.

formatValue

public java.lang.String formatValue()

This method returns the value of the attribute as string in user friendly formatted way. When an attribute value formatter ist set, this formatter is used to format the returned value. Otherwise the string representation of the attribute value is returned.

Specified by:

formatValue in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The formatted attribute value.

See Also:

AttributeInterface.setAttributeValueFormatter(AttributeValueFormatInterface), AttributeInterface.getValueAsString()

getDisplayKeyword

public java.lang.String getDisplayKeyword()

This method returns the display keyword of the attribute. The display keyword is used to identify the attribute in error messages or at user interfaces.

Specified by:

getDisplayKeyword in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The display keyword.

getDisplayKeyword

public java.lang.String getDisplayKeyword(java.util.Locale locale)

This method returns the display keyword of the attribute in the passed locale. The display keyword is used to identify the attribute in error messages or at user interfaces.

Specified by:

getDisplayKeyword in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

locale - The locale of the display keyword.

Returns:

The display keyword.

getKeyword

public java.lang.String getKeyword()

This method returns the keyword of the attribute. The keyword identifies the attribute uniquely in its component.

Specified by:

getKeyword in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The keyword.

getMode

public AttributeMode getMode()

This method returns the mode of the attribute.

Specified by:

getMode in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The attribute mode.

getType

public java.lang.String getType()

This method returns the type of the attribute as string.

Specified by:

getType in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The type string.

getTypeInfo

public java.lang.String getTypeInfo()

This method returns the attribute type, the mode character and the value information in one string separated by comma.

Specified by:

getTypeInfo in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The string containing the attribute type and the value information.

See Also:

AttributeInterface.getTypeInfo(), AttributeInterface.getMode(), AttributeInterface.getValueInfo()

getValueAsString

public java.lang.String getValueAsString()

This method returns the string representation of the attribute value. The string representation should be accepted by th method AttributeInterface.setValueWithString(String).

The implementation here returns the empty string.

Specified by:

getValueAsString in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The empty String.

getValueInfo

public java.lang.String getValueInfo()

This method returns the valid values for the attribute. The returned string depends on the attribute type. A integer attribute for example may return the minimum and maximum value, an enumeration attibute the value list.

The implementation here returns the empty string.

Specified by:

getValueInfo in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

The empty String.

isValueEqual

public boolean isValueEqual(A otherAttribute)
                     throws AcafException

This method implements the interface AttributeInterface and compares the value of the passed attribute with the value of this attribute. This implementation compares the string representation of the attributes returned by the the method getValueAsString(). When the strings are equal, the method returns true.

Specified by:

isValueEqual in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

otherAttribute - The attribute to be compared with this attribute.

Returns:

true if the attribute values are equal, otherwise false.

Throws:

AcafException - May be thrown by derived classes.

See Also:

ComponentInterface.isComponentEqual(ComponentInterface)

isReadonly

public boolean isReadonly()

This method returns true if the attribute mode is AttributeMode.READ_ONLY, otherwise false.

Specified by:

isReadonly in interface AttributeInterface<A extends AttributeInterface<?>>

Returns:

true if the attribute mode is AttributeMode.READ_ONLY, otherwise false.

notifyObservers

protected void notifyObservers()

This method notifies all observer objects about the attribute value change. It calls the method AttributeObserver.attributeChanged(AttributeInterface) for all observers. Observers are managed in a linked list and are always notified in the same order. Observers can remove itself calling the method detachObserver(AttributeObserver) while they are notified by this method. Observers can be attached more than once. They are notified as often as they appear in the observer list. Observers are notified in the order they are attached.

setAttributeValueFormatter

public void setAttributeValueFormatter(AttributeValueFormatInterface<? super A> formatter)

This method can be used to set a custom value formatter. If set to null (as initially) this means that the framework mechanisms will be used that are implemented for the different attribute types.

Specified by:

setAttributeValueFormatter in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

formatter - The attribute value formatter.

setValueWithString

public void setValueWithString(java.lang.String newValue)
                        throws AttributeException

This method converts the passed string representation of the attribute value to the specific attribute value. The method should accept the string representation returned by the method AttributeInterface.getValueAsString().

This implementation here is empty.

Specified by:

setValueWithString in interface AttributeInterface<A extends AttributeInterface<?>>

Parameters:

newValue - The string representation of the new attribute value.

Throws:

AttributeException - My be thrown by the implementing classes when converting the string representation or setting the attribute value fails.