Builders and inheritance

• In a class hierarchy, both superclasses and subclasses can have their own constructors.

• The superclass constructor is responsible for constructing the part of the object that corresponds to the superclass.

• The subclass constructor is responsible for constructing the part of the object that corresponds to the subclass.

• In practice, object construction is done in two steps: first, the superclass is constructed and then the subclass.

• If only the subclass defines a constructor, the superclass constructor is automatically called to construct the superclass part of the object, using the superclass's default constructor.

• Example: Here is a version of the Triangle class that defines a constructor and makes style private, being set by the constructor.

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