Can someone explain this UML diagram

class-diagram, uml

Solution

First of all, could you please provide the source of your class diagram implementation, your inputs are not clear enough to determine the realtionships between the classes.

- (A) There are two types of arrows, the arrow with a rectangular head describes "Generalization".

The specific classifier inherits part of its definition from the general classifier. The general classifier is at the arrow end of the connector. Attributes, associations, and operations are inherited by the specific classifier. Use the Inheritance tool to create a generalization between two classifiers.

- The second type of arrows describes "Association"

A relationship between the members of two classifiers. There are two types of it, Aggregation and Composition.

- (B) The numbers beside arrows simply describes "Multiplicity"

Multiplicity of an association end is the number of possible instances of the class associated with a single instance of the other end.

  ┬─────────────────────────┬───────────────────────────────────────────────────────┬
  │  Multiplicities         |      Explanation                                      |
  │                         |                                                       | 
  ├─────────────────────────┼───────────────────────────────────────────────────────┼
  |0..1                     | zero or one instance.                                 | 
  ├─────────────────────────┼───────────────────────────────────────────────────────┼
  |0..*  or  *              | no limit on the number of instances (including none)  | 
  ├─────────────────────────┼───────────────────────────────────────────────────────┼
  |1                        | exactly one instance                                  | 
  ├─────────────────────────┼───────────────────────────────────────────────────────┼
  |1..*                     | at least one instance                                 | 
  ├─────────────────────────┼───────────────────────────────────────────────────────┼

You can find helpful examples in the links below.

Explanation of the UML arrows

http://msdn.microsoft.com/en-us/library/dd409437%28VS.100%29.aspx

http://edutechwiki.unige.ch/en/UML_class_diagram

Problem

This is embarrassing, I apologize for not including the diagram image ( I thought I included it, but I should be more careful and verify it in the post ) I know almost nothing about UML, but to my knowledge an arrow with hollow head represents inheritance relationship ( ie `ANDSpecification` class inherits from `CompositeSpecification` class ), while the other type of arrow tells us we can navigate from `ANDSpecification` to `CompositeSpecification`? a) But why does the diagram connecting `ANDSpecification` and `CompositeSpecification` contain both types of arrows? Perhaps because in addition to `ANDSpecification` inheriting from `CompositeSpecification`, it also has a property of type `CompositeSpecification`? b) What is the meaning of numbers next to arrows?

Original source

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