oracle.dss.rules
Class Rule

java.lang.Object
  |
  +--oracle.dss.rules.Rule

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

Direct Known Subclasses:

DiscriminatorRule

public class Rule

extends java.lang.Object

implements java.io.Serializable, java.lang.Cloneable

An object that specifies:

• A set of property values to be used when a DataView paints an item
• Information about the conditions under which the values should be used

The property values are specified in a Mergeable object. The applies method specifies whether the properties in the Mergeable should be used. In this class, the applies method always returns true, so the rule always applies.

Rule objects are normally stored in RuleBundle objects. RuleBundle objects are stored in vectors, which are then passed to a Manager class, which runs all the rules in all of the rule bundles. The result is a single Mergeable object that specifies all of the settings that the Manager should use to paint an item in a DataView.

Subclasses of this class can override methods, in order to produce more specific rules. For example, the DiscriminatorRule specifies conditions under which the rule applies.

Dynamic rules can be created by overriding the runRule method and the fireRule method. For example, you might want a rule that sets the background color of a table cell, based on a data value. You could have the fireRule method set the Background property of its internal ViewStyle (a Mergeable object) dynamically, based on the data value of the cell that is to be painted.

See Also:

Mergeable, DiscriminatorRule, RuleBundle, Serialized Form

Field Summary

static int	RESET_EVERYTHING Reset all defaults, so that the rule is equivalent to one that has just been created.
static int	RESET_NONE Reset no defaults.
static int	RESET_XML_PROPERTIES Reset defaults for properties that can be set through XML.

Constructor Summary

Rule()
Constructor that does not specify a Mergeable object.

Rule(Mergeable mergeable)
Constructor that specifies a Mergeable object.

Method Summary

boolean	applies(RuleContext context, Mergeable target) Specifies whether this rule applies in the specified context.
java.lang.Object	clone() Clones this object.
void	fireRule(RuleContext context, Mergeable target) Modifies the specified Mergeable object to include property settings that this Rule specifies.
Mergeable	getFixedMergeable() Retrieves the Mergeable object that specifies property settings that should take effect when this Rule applies.
interface	getXML(boolean allProperties, ComponentTypeConverter converter) Retrieves XML that represents properties and their values in the form of and ObjectNode.
boolean	runRule(RuleContext context, Mergeable target) Fires this rule if the specified context warrants.
void	setFixedMergeable(Mergeable mergeable) Specifies the Mergeable object whose property values should be set whenever this Rule applies.
boolean	setXML( objectNode, java.lang.String version, int reset) Specifies XML that represents properties and values.

Methods inherited from class java.lang.Object

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

Field Detail

RESET_NONE

public static final int RESET_NONE

Reset no defaults.

RESET_XML_PROPERTIES

public static final int RESET_XML_PROPERTIES

Reset defaults for properties that can be set through XML.

RESET_EVERYTHING

public static final int RESET_EVERYTHING

Reset all defaults, so that the rule is equivalent to one that has just been created.

Constructor Detail

Rule

public Rule()

Constructor that does not specify a Mergeable object. If you call this constructor, and the rule needs a Mergeable object, then you must also call the setFixedMergeable method.

See Also:

setFixedMergeable(oracle.dss.rules.Mergeable), Mergeable

Rule

public Rule(Mergeable mergeable)

Constructor that specifies a Mergeable object.

Parameters:

mergeable - The Mergeable object whose property values should be used when this rule applies.

Method Detail

clone

public java.lang.Object clone()

Clones this object. Subclasses of this class must override this method. Not doing so leads to unexpected behavior.

Returns:

The clone of this object.

applies

public boolean applies(RuleContext context,
Mergeable target)
                throws RuleException

Specifies whether this rule applies in the specified context. Subclasses should override this method, because in this class, this method always returns true.

Parameters:

context - The context of the item that is to be painted. The DataView provides this parameter.

target - The Mergeable object whose properties will be modified when the rule is fired, if this method returns true. Overriding methods may or may not use this parameter. This must be the same class as the object retrieved by calling the getFixedMergeable method.

Returns:

true. Overriding methods should return true or false.

Throws:

RuleException - If context is unusable for some reason or if this Rule has a problem.

runRule

public boolean runRule(RuleContext context,
Mergeable target)
                throws RuleException

Fires this rule if the specified context warrants. This method calls the applies method. If the applies method returns true, then this method calls the fireRule method.

The RuleBundle method calls this method for each rule in the bundle. Extending classes may or may not choose to override this method. (An implementation might skip the call to applies altogether and just call fireRule.)

Parameters:

context - The context of the item that is to be painted. The DataView provides this parameter.

target - The Mergeable object whose properties will be modified when the rule is fired, if this method returns true. Included in case the applies method wants to examine the Mergeable. This must be the same class as, or a subclass of, the object retrieved by calling the getFixedMergeable method.

Returns:

true if the applies method returns true, false if not.

Throws:

RuleException - If context is unusable for some reason or if this Rule has a problem.

fireRule

public void fireRule(RuleContext context,
Mergeable target)
              throws RuleException

Modifies the specified Mergeable object to include property settings that this Rule specifies. This implementation merges the specified Mergeable object with the Mergeable object of this Rule. Merging the two objects adds the property settings from this Rule to those property settings that will be used when the DataView paints an item.

Parameters:

context - The context of the item that is to be painted. The DataView provides this parameter. Subclasses might examine the context to determine how to modify the Mergeable object.

target - The Mergeable object whose properties will be modified. This must be the same class as, or a subclass of, the object retrieved by calling the getFixedMergeable method.

Throws:

RuleException - If context is unusable for some reason or if this Rule has a problem.

getFixedMergeable

public Mergeable getFixedMergeable()

Retrieves the Mergeable object that specifies property settings that should take effect when this Rule applies.

Returns:

The Mergeable that specifies the property settings for this Rule.

setFixedMergeable

public void setFixedMergeable(Mergeable mergeable)

Specifies the Mergeable object whose property values should be set whenever this Rule applies.

Parameters:

mergeable - The object that specifies property values that should be set whenever this Rule applies.

getXML

public getXML(boolean allProperties,
ComponentTypeConverter converter)

Retrieves XML that represents properties and their values in the form of and ObjectNode.

Parameters:

allProperties - true to store all property values in XML, false to store only values that are different from default values.

converter - A class that converts view component identifiers from strings to integers and back. Dataview objects implement the ComponentTypeConverter interface.

Returns:

XML for the properties and values.

setXML

public boolean setXML( objectNode,
                      java.lang.String version,
                      int reset)

Specifies XML that represents properties and values. This method applies the values of the properties in the XML to this Rule.

Parameters:

node - ObjectNode that has the properties and their values.

version - The XML version.

reset - A constant that indicates how much to reset when XML is applied. Valid values are listed in the See Also section.

Returns:

true if XML is properly applied, false if the XML cannot be applied.

See Also:

RESET_NONE, RESET_XML_PROPERTIES, RESET_EVERYTHING