Annotated Java Code Samples

Code samples on the basic features of Java necessary to get started with programming.

• HelloWorld.java Main method, how print statements work.
• ClassesAndObjects.java How to declare classes and what objects are.
• Types.java Primitive vs. references types and why this matters.
• Methods.java How to declare methods, static vs. instance methods.
• Importing.java How import statements work.
• EnumTypes.java How enum types work.
• ExceptionHandling.java Basics of exception handling.
• Generics.java Introduction to generic types.

Sample program that outputs the text of the poem "The Twelve Days of Christmas" to the console.

• TwelveDays.java Main method, basic Java library methods, method parameters, recursion.

Code samples focused on illustrating how to decompose a system into distinct, manageable abstractions.

• Card.java Encapsulation, information hiding, design by contract,...
• Deck.java Mutable fields, assert statements, unmodifiableList,...
• Rank.java Enumerated type.
• Suit.java Another example of enumerated type.

Code samples that illustrate best practice for organizing code effectively using types and interfaces.

• Card.java Classes, interface implementation, comparable behavior, anonymous classes.
• CardSource.java Java interfaces, implicitly public methods.
• Client.java Sample code that uses classes.
• Deck.java Iterable data structures, working with lists, comparable behavior.
• Rank.java Enumerated type.
• Suit.java Another example of enumerated type.

Code samples that clarify what object state is and how we can manage it in a principled way.

• Card.java Flyweight pattern, static initialization, private constructors...
• CardSource.java Java interfaces, constants, Null Object pattern, default methods...
• Client.java Null Object pattern, instances of inner classes.
• Deck.java Static factory method, anonymous classes, variable capture.
• GameModel.java Singleton design pattern.
• Rank.java Enumerated type.
• Suit.java Another example of enumerated type.

Code samples on metaprogramming with reflection and unit testing with JUnit.

• AbsTest.java A basic unit test, unit test annotations, naming conventions...
• Card.java Code under test (not annotated).
• FoundationPile.java Code under test (not annotated).
• Client.java Code under test (not annotated).
• MetaprogrammingSamples.java Metaprogramming, class Class, type wildcards.
• Move.java Code under test (not annotated).
• PlayingStrategy.java Code under test (not annotated).
• Rank.java Code dependency (not annotated).
• Suit.java Code dependency (not annotated).
• TestFoundationPile.java Test scaffolding, test lifecycle, testing with exceptions, unit test design tips.
• TestGameModel.java Testing with stubs.

Code samples showing how to build functionality by composing objects.

• Card.java Code dependency (not annotated).
• CardSource.java Example of an interface that includes polymorphic copying.
• CardStack.java Wrapper around a list (not annotated).
• Command.java Element of the Command design pattern, optional types.
• CompositeCardSource.java Composite design pattern, varargs.
• Deck.java Non-static command factory.
• GameModel.java Polymorphic copying.
• LoggingDeck.java Composition within a type hierarchy (not annotated).
• LoggingDecorator.java Decorator design pattern.
• MemorizingDecorator.java Decorator design pattern.
• Rank.java Code dependency (not annotated).
• Suit.java Code dependency (not annotated).

Code samples showing how inheritance works and how to use it properly.

• AbstractDecorator.java Abstract classes, protected visibility.
• AbstractMove.java Template Method design pattern, abstract methods.
• Card.java Code dependency (not annotated).
• CardMove.java Final classes.
• CardSource.java Code dependency (not annotated).
• CardStack.java Code dependency (not annotated).
• Deck.java Code dependency (not annotated).
• GameModel.java Code dependency (not annotated).
• LoggingDecorator.java Decorator design pattern with inheritance.
• MemorizingDeck.java Inheritance with method overriding and super calls.
• Move.java Code dependency (not annotated).
• Rank.java Code dependency (not annotated).
• Suit.java Code dependency (not annotated).

Code samples showing different applications of inversion of control, through the Observer and Visitor design patterns.

• AbstractCardSourceVisitor.java Default behavior for visitor implementations.
• AceDetector.java Sample observer object.
• Card.java Code dependency (not annotated).
• CardSequence.java Code dependency (not annotated).
• CardSource.java accept method in Visitor pattern.
• CardSourceVisitor.java Visitor interface.
• CardStack.java Code dependency (not annotated).
• CardStackObserver.java Example of abstract observer.
• ChecksContainmentVisitor.java Example of concrete visitor.
• CompositeCardSource.java Code dependency (not annotated).
• Counter.java Sample observer object.
• CountingVisitor.java Concrete visitor with state accumulation.
• Deck.java Code dependency (not annotated).
• Driver.java Client code that uses different visitors.
• GenericVisitorSample.java Implementation of the Visitor pattern with generic types.
• LuckyNumber.java Sample JavaFX GUI program based on the Observer pattern.
• ObservableCardStack.java Support for the Observer pattern using inheritance.
• PrintVisitor.java Very simple application of the Visitor pattern.
• Rank.java Code dependency (not annotated).
• StructurePrinterVisitor.java Visitor that prints a representation of the hierarchical structure of a composite object.
• Suit.java Code dependency (not annotated).

Code samples about functional-style programming in Java.

• AutoPlayer.java Strategy pattern in functional style.
• Card.java Comparison behavior in functional style.
• CardSelectionStrategy.java User-defined functional interface.
• CardSource.java Code dependency (not annotated).
• CardStack.java Code dependency (not annotated).
• CardUtils.java Code dependency.
• ConsumingDecorator.java Use of the Consumer interface in Decorator design pattern.
• Deck.java Defining streaming methods in a class's interface.
• Filter.java Simple functional interface.
• InfiniteCardSource.java Use of the Supplier interface.
• ObservableDeck.java Observer design pattern in functional style.
• Rank.java Code dependency (not annotated).
• Samples.java Multiple samples of code in functional style.
• Suit.java Code dependency (not annotated).