1.18 WordLibraries Facade

Juppies 2 by Dr Heinz M. Kabutz

Next we look at the WordLibraries class. Note that this is written in the plural form, which usually means that it is a class that will be used to manage other classes that have something to do with the WordLibrary class that we saw earlier. The correct technical name for this type of class is a Facade, a well-known design pattern that often occurs in Java. The WordLibraries class has a private constructor. So how can we make new objects if the constructor is private? We cannot. That's the point of making the constructor private. The class is also final, although no one would be able to subclass it anyway since the constructor is private. The final on the class is thus a bit redundant. However, it is quite common for a Facade to also be final.

The way that we use the WordLibraries class is to call the static method createDefaultWordLibrary(). Because it is static, we call it on the class itself, not on an object. Thus, when we create our default WordLibrary object we do it simply with: WordLibraries.createDefaultWordLibrary().

In Java, the naming convention is that fields, local variables and parameters to methods typically start with lower case letters and use CamelCase. Classes start with a capital letter and use CamelCase. When I read WordLibraries.createDefaultWordLibrary() I know that this is a method called on a class, thus a static method, without looking at the definition of the method. Please please please please please please please please please please please please please follow this convention in your code. Have classes start with an upper-case letter and fields / local variables / method parameters start with a lower-case letter. Even if you come from a language that does it differently, when coding Java, please use our convention, otherwise you will confuse us horribly when we try to figure out what your code is doing.

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Table of Contents

• 0.1: Programming is a team sport - source control
• 0.2: Creating an account on GitHub
• 0.3: Forking the Juppies2 repository from kabutz
• 0.4: Oracle JDK
• 0.5: Oracle OpenJDK
• 0.6: Azul's Zulu OpenJDK
• 0.7: Installing the Oracle OpenJDK
• 0.8: Integrated Development Environments (IDEs)
• 0.9: Downloading Apache NetBeans
• 0.10: Loading our Juppies2 Project in Apache NetBeans
• 0.11: Running the AnagramGame with Apache NetBeans
• 0.12: Downloading IntelliJ IDEA Community Edition
• 0.13: Installing IntelliJ IDEA Community Edition
• 0.14: Running the AnagramGame with IntelliJ IDEA Community Edition
• 0.15: Downloading and Installing Eclipse
• 0.16: Running the AnagramGame with Eclipse
• 1.1: AnagramGame Project Structure
• 1.2: WordLibrary
• 1.3: Swing User Interface (UI)
• 1.4: Buffer Overflows
• 1.5: Demo of New Word Button
• 1.6: Demo of Guess Button
• 1.7: StaticWordLibrary Structure
• 1.8: StaticWordLibrary Details
• 1.9: Changing the Size of Our StaticWordLibrary
• 1.10: How my Buffer Overflow Wiped my Colleague's Hard Disk
• 1.11: Adding Our Own Words to the StaticWordLibrary
• 1.12: WordLibraryTest With JUnit
• 1.13: Java's For Loop
• 1.14: Testing That Words Are Anagrams
• 1.15: Running JUnit
• 1.16: isAnagram() Method
• 1.17: Fixing StaticWordLibrary
• 1.18: WordLibraries Facade
• 1.19: Find Usages
• 1.20: Exercise
• 1.21: Commiting Changes
• 1.22: GitHub Repository
• 1.23: Pushing Commits to Remote Repository on GitHub
• 1.24: Until Next Time
• 2.1: Welcome back
• 2.2: Setting up NetBeans Git Toolbar
• 2.3: Creating a Git Branch for Today's Session
• 2.4: Typical Directory Structure Under Maven
• 2.5: NetBeans Magic Shortcuts
• 2.6: Avoid Copy & Paste Programming
• 2.7: Creating a ShuffledWordLibrary
• 2.8: Integer Array for Shuffled Indexes
• 2.9: Finishing the methods to delegate to the other WordLibrary
• 2.10: Trying out the "ShuffledWordLibrary" That Does Not Really Shuffle
• 2.11: Committing Our Changes to Git
• 2.12: Shuffling the Integer Array
• 2.13: Trying Out the Shuffled Anagram List
• 2.14: Committing our "shuffle" method
• 2.15: ArrayShuffler
• 2.16: Creating an ArrayShufflerTest
• 2.17: Printing the indexes array
• 2.18: Fixing Random to be more random
• 2.19: Extending the Tests
• 2.20: The Goat, The Wolf and The Cabbage (Swapping Integer Values)
• 2.21: Testing the Integer Swapping Code
• 2.22: Testing Before Running Application
• 2.23: Fixing the Integer Swapping Code
• 2.24: Integer Swapping With XOR
• 2.25: Value of Source Control Systems
• 2.26: Changed WordLibrary from an Abstract Class to an Interface
• 2.27: Commit and Push
• 2.28: Until Next Time
• 3.1: Welcome back
• 3.2: Create a new Git Branch
• 3.3: ScrambledWordLibrary
• 3.4: SortedScrambledWordLibrary
• 3.5: Committing Entire Project At Once
• 3.6: Creating a RandomScrambledWordLibrary
• 3.7: Adding a shuffle(char[]) method
• 3.8: Testing the shuffle() method
• 3.9: Scrambler Strategy Extracted
• 3.10: Rot13Scrambler
• 3.11: OriginalScrambler
• 3.12: Moving Scrambler Interface Into ScrambledWordLibary Using IntelliJ IDEA
• 3.13: Moving Shuffler Implementations Into ScrambledWordLibrary
• 3.14: Danger of Overusing Inner Classer
• 3.15: Testing Refactoring
• 3.16: Beauty of IDE Interoperability
• 3.17: Anonymous Inner Classes
• 3.18: Converting Anonymous Inner Class to Lambda
• 3.19: Expression Lambdas
• 3.20: Font Ligatures
• 3.21: Testing and Commiting Lambdas
• 3.22: Turning Rot13Scrambler into a Lambda
• 3.23: Method References
• 3.24: Making ArrayShuffler.shuffle() Methods static
• 3.25: Forcing Everyone To Use Static Methods
• 3.26: DecoratedWordLibrary
• 3.27: ScrambledWordLibrary as a Decorator
• 3.28: ShuffledWordLibrary as a Decorator
• 3.29: Cleaning Up the Concrete Decorators
• 3.30: Updated Copyright Notices
• 3.31: Make Classes Final Where Possible
• 3.32: Commit and Push
• 3.33: Conclusion

We hope you enjoyed this tutorial. If you did, you will also enjoy our courses. We suggest you start with Extreme Java - Advanced Java, followed by Extreme Java - Concurrency Performance for Java 8.