Using super to call superclass constructors

• A subclass can call a constructor defined by its superclass using the form super(parameter-list);.

• parameter-list must specify the parameters needed by the superclass constructor.

• The first statement executed within the constructor of a subclass must always be super(); (or super(parameter-list); if it is necessary to pass parameters).

• The following is a version of TwoDShape with a constructor that initializes width and height.

• The Triangle subclass uses super(w, h) to call the constructor of the TwoDShape superclass, passing the values ​​of w and h.

• TwoDShape's constructor initializes width and height with these values.

• The Triangle subclass does not need to initialize width and height, just the style value, which is exclusive to it.

• Using super( ) allows the superclass (TwoDShape) to construct its own subobject as desired and add functionality without the subclass needing to know the details.

• Every form of constructor defined by the superclass can be called with super( ). The constructor executed will be the one whose arguments match the given parameters.

• The following example shows expanded versions of TwoDShape and Triangle with default constructors and constructors that take one argument.

• Call to the Superclass Constructor: When a subclass calls super( ), it is invoking the constructor of its immediate superclass.

• Reference to Immediate Superclass: super( ) always references the superclass immediately above the class that is calling it, even in multi-level hierarchies.

• First Instruction in the Constructor: super( ) must be the first instruction executed within the constructor of a subclass. This ensures that the superclass part of the object is initialized before the subclass constructor executes its own code.

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