CS1021 - Inheritance Review

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    class: taylor msoe
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    class: center, middle

.title[
      # Inheritance Review
    ]

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Toggle speaker view by pressing P

Pressing C clones the slideshow view,
    which is the view to put on the projector
    if you're using speaker view.

Press ? to toggle keyboard commands help.

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    # Inheritance
    * A relationship between classes

--
    * Super class - more generalized type

--
        + `Animal`
    --
    * Sub classes - more specific types of the super class

--
        + `Dog`
        + `Gnat`
        + `Robin`
    --
    * Sub class **is-a** super class

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    # Motivation for Inheritance
    * Code reuse

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    * Identify similar but not identical types

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    * Use general reference to point to specific object type

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    class: animated slideInUp center, middle

* Consider [javafx.scene.control.Button](https://openjfx.io/javadoc/11/javafx.controls/javafx/scene/control/ButtonBase.html)

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    class: center, middle

* Open triangle signifies inheritance (points to super class)

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    * See the Javadoc for the [javafx.scene.control.Button](https://openjfx.io/javadoc/11/javafx.controls/javafx/scene/control/ButtonBase.html) class

## Code reuse
    * Properties managed by `Control`:
        + contextMenu
        + skin
        + toolTip
    * Properties managed by `Labeled`:
        + font
        + graphic
        + lineSpacing
        + etc...
    * Properties managed by `ButtonBase`:
        + armed
        + onAction

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    # Benefits of Inheritance
    ## Identifying similar but not identical types

* `Separator`, `MenuBar`, `Labeled`, `ScrollPane`, `ListView`, and `ToolBar` are all specific types of `Control`s

## General ref can point to specific object type
    ```
    Control control = new Separator();
    Labeled labeledControl = new Label("I'm an enigma");
    ButtonBase button = new Button("I'm not a dress shirt");
    button = new CheckBox("I don't play hockey");
    control = button;
    button = labeledControl; // <-- Illegal since a labeled control may not be a button
    ```

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    ## Analogies
    * I can refer to my daughter as my child
    * I can refer to my maternal grandfather as my ancestor
    * I can refer to my iPhone 8 plus as my cell phone or just phone

## Jokes explained
    * An enigma - defies labeling
    * A shirt - needs to be pressed (ironed)
    * Hockey - I don't want to get hurt by being checked

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    # Code Reuse

```
    javafx.scene.control.Control
        javafx.scene.control.Labeled
            javafx.scene.control.ButtonBase
                javafx.scene.control.Button
    ```

* Functionality shared by all objects that are `Control`s is implemented in the `Control` class

--
        + E.g., `setToolTip()`
    --
    * Functionality shared by all objects that are `Labeled` controls is implemented in the `Labeled` class

--
        + E.g., `setText()`

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    # Code-Reuse Classes
    * It may make sense to create a super class solely to promote code reuse

--
    * The `ButtonBase` class exists solely for code reuse

--
        + All buttons (buttons, hyperlinks, checkboxes, radio buttons, etc...) need to respond to actions
        + `ButtonBase` manages what code should be run when the button is pressed
        + Classes with _Base_ or _Abstract_ in the name are typically created to promote "code reuse"

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    # Synonyms
    * Super class ↔ Parent class
    * Sub class ↔ Child class
    * `B` extends `A` ↔ `B` derives from `A` ↔ `B` is a sub class of `A`