Polymorphism and Application to GUIs PDF

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David Johnson...

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Lecture 30: Polymorphism and application to GUIs ●

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Polymorphism ○ Generics are a form of polymorphism ○ Operator are a form of polymorphism because ○ Subtype polymorphism References in polymorphism ○ A hava reference can reference a class or any subclass of that class ○ The object that is reference contains info for its class and any super classes Methods ○ A method call is checked in two ways ■ At compile time, the reference type is used to see if the method exists in the reference type class ■ At run time, the reference object method is called Why do this? ○ We want to make general purpose code An application of inheritance ○ Making an user interface ○ Java has an extensive library for user interfaces ■ Java Swing ● There are other similar libraries ■ Will discuss larger structure soon Make an overall application ○ Make a JFrame ■ Window ○ Add the button to it ○ Show it...