Packages and scope
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Packages and Scope - Introduduction to Jave Programming - Lecture Slides, Slides of Java Programming
In the course of the Introduction to Jave Programming, we study the basic syntax and the basic program in java. In these lecture slides the key points are: Packages, Javadoc, References, Memory, Locations, Solutions on Moodle, Mastering References, Matryoshka Doll, Null, Copying
Typology: Slides
2012/2013
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Packages and scope
Halloween
Highlights
- protected / package scope
Review: Inheritance
Review: Override
Child classes can override methods from their parent's class This means a child can redefine a method to work in a completely different way than the parent's method Can use super to get the parent's version of an overridden method
final
We have used final to declare constants (objects who's value cannot change) You can use the final modifier with methods and classes as well: final classes cannot be the parent for any class final methods cannot be overridden (See: Final.java, FinalClass.java and FinalMethod.java)Docsity.com
Scope modifiers
Var Scope A.x = Any class A.y = Only A B.y = Any class B.z = B, C and any in package C.w = Any in package D.z = Any in package E.x = Any class (See: A, B, C, D.java)Docsity.com
Scope modifiers
Good picture on page 457 of textbook
Some scope oddities
Suppose C extends A...
- C can access protected variables in A directly
- C can access protected variables inherited from A in an instance of C
- C cannot access protected variables from A in an instance of A (See: C.java)
Why should I care about scope?
If you are writing a simple program that only you, yourself, will use... then you do not. But imagine if all programs gave full access to everything...