Answer

• Association Class:An association class allows you treat an association itself as a class , and model it with attributes, operations, and other features. It is illustrated with a dashed line from the association to the association class. For example Company Class associated with Person with association class Hire. 
• Singleton Class: A class which ensure that only once instance to be created in the life cycle of application. In class diagram this class is marked with a '1' in the upper right corner of the name compartment. AppConfigurations class in any application usually keep the settings of the application and is implemented as singleton class. 
• Active Class: An active object runs on and controls its own thread of execution. The class of an active object is an active class. It is shown with double vertical lines on the left and right sides of the class box in class diagram. For example any class that implements Runnable interface in JAVA or extends Thread class is an active class. 
• Concrete Class: Usually a class that implement an interface or another abstract class is called a concrete class in object desinging, However a non-abstract class is also a concrete class. For example Student in CUONLINE is a concrete class.

Answer
Every classifier in the class diagram relate to another classifier through one of the following relationship:

Answer
Operations

• Shown in one compartment with following format
• visibility name (parameter-list) {property-string} UML 1
• visibility name (parameter-list) : return-type {property-string} UML 2
• Operations are usually assumed public if no visibility is shown
• UML allows the operation signature to be written in any programming language
• + getPlayer( name : String ) : Player {exception IOException}
• public Player getPlayer( String name ) throws IOException
• An operation is not a method, It’s a declaration, with a name, parameters, return type, exceptions list, and possibly a set of constraints of pre-and post-conditions

• Methods are implementations
• Shown in following ways
• in interaction diagrams, by the details and sequence of messages
• in class diagrams, with a UML note symbol stereotyped with «method»
• Method is part of dynamic modeling

• The create Operation in DCDs is mapped to the constructor definition
• Operations to Access Attributes are skipped to reduce noise i.e. getPrice, setPrice
  

Answer

• Shown in one compartment with following format:
• visibility name (parameter-list) {property-string} UML 1.
• visibility name (parameter-list) : return-type {property-string} UML 2
• Operations are usually assumed public if no visibility is shown
• UML allows the operation signature to be written in any programming language
• + getPlayer( name : String ) : Player {exception IOException}
• public Player getPlayer( String name ) throws IOException
• An operation is not a method, It’s a declaration, with a name, parameters, return type, exceptions list, and possibly a set of constraints of pre-and post-conditions

Answer
May represent several one of the following:

• UML note or comment, which by definition have no semantic impact
• UML constraint, in which case it must be encased in braces '{…}’
• A method body the implementation of a UML operation

Answer

• Use the attribute text notation for data type objects and the association line notation for others.
• The end of an association can have a navigability arrow, optional rolename (attribute name) and may also show a multiplicity value
• Collection Attributes with Attribute Text and Association Lines can be shown using
• Text notation format e.g. salesLineItems : SaleLineItems[1..*]{ordered}
• Adding property string ({ordered, List}) to the end arrow of association line

Answer
Attributes of a classifier are shown in following ways:

• Attribute text notation
• Attributes are usually assumed private if no visibility is given
• visibility name : type
• such as currentSale : Sale.
• Association line notation
• a navigability arrow pointing from the source to target object
• a multiplicity at the target end, but not the source end
• a rolename (currentSale) only at the target end to show the attribute name
• Both together