UML graphics
a ) Class (class): The class name shown in italics is abstract class, " + " is public , " - " is private , and " # " is protected . The first behavior is the class name; the second behavior is the characteristic (field or property); the third behavior is the operation (method or behavior). For abstract classes, class names are in italics.
b ) Interface (interface): There is an " interface " at the top of the interface to distinguish it from a class, or a label in the form of a lollipop.
c ) Inheritance: The hollow triangle + solid line is the inheritance relationship. Birds inherit the characteristics of animals.
d ) Implement the interface: hollow triangle + dashed line. Such as the realization of the flying interface.
e ) Association can be used when one class needs to know about another class . Use solid arrows. For example, penguins are associated with climate, because penguins need to know the climate.
f ) Aggregation vs Composition : _ _
- Aggregation is a weak "owning" relationship, ie: A object can contain B object, but B object is not part of A object. Each individual contained in the A object can exist independently from the A object . Indicated using open diamonds + solid arrows. Like a flock of geese assembled by geese.
- Composition is a strong "owning" relationship, ie: B object is part of A object. have the same life cycle. Indicated using solid diamonds + solid arrows. Such as wings are part of a bird.
- Aggregation and Composition can have cardinality.
g ) Dependency ( Dependency ): represented by a dotted arrow , pointing to the dependent object. Such as animals depend on oxygen, water.
Summarize:
It can be seen from the above that no matter what the relationship is, such as association, composition, aggregation, etc., it is also realized through polymorphism, abstraction, and inheritance in object-oriented languages.
The association, composition, aggregation, etc., although the meanings are different, are mostly implemented in the code by defining another object (or its reference, pointer) in one object.
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