Back to Seminar Tasks 2 & 3

• Relatively straightforward
  • Especially Task 2
• Copy & Paste worked well
  • Still there were some challenges - where?

Back to Seminar Task 4

• Completely different story
  • Many of you struggled significantly
  • Why was that?
• Copy & Paste still necessary
  • Are the abstractions friendly?
• You may have reached your Java limits

So why do we need the Renderer concept?

• Isn't Object.toString() enough?
  • Its audience are developers (logs, debugging, ...)
  • NEVER expose toString() products to end users!
• Different components may require different format
  • And customer-facing strings may be localized

AbstractRenderer benefits

• Shields you from ugly Swing API
  • ListCellRenderer<T>
  • TableCellRenderer
• Brings type safety on top of old API
• Feel free to reuse AbstractRenderer in your projects
  • As well as other abstractions you find useful

Filtering in Swing

• RowSorter abstraction API too wide
  • Both sorting and filtering
• RowFilter still too vague
  • EntityMatcher adapts it from rows to entities

Additional complexity

• Heterogeneous data in filters
  • Distinct objects (enums or entities)
  • Groups (all distinct objects or their subsets)
  • Leading to abstraction Either<L, R>
• Functional API
  • Lambdas & Streams
  • Optional

Layered Architecture

Layered Architecture

Each layer of the layered architecture pattern has a specific role and responsibility within the application.[1]

Open-Closed Principle

• Definition
  • Software entities should be open for extension, but closed for modification
• What does it mean?
• How to achieve that?

N-tier architecture

Separation of concerns

Layers of isolation

Architecture sinkhole anti-pattern

Error Handling

• What is and why we need error handling?
• Best practices
• Checked vs Unchecked exceptions
• Demo

Work with files

• Existing API
• Resource leaks
• try-with-resources

Comments in Java

• Documentation vs Implementation
• Best practices
• Demo

Recommended reading

Effective Java (Third Edition)

Joshua Bloch

Addison-Wesley Professional, 2017

https://www.amazon.com/dp/0134685997

Effective Java

• Book not only about Java
  • Almost half of the book is about OOP in general
  • Present since 2001 (the first edition)
  • With code examples specifically in Java
• Items are heavily cross-referenced
  • Start reading anywhere you like

Josh Bloch (the author)

• Java architect between 1996 and 2004
• Designed a lot of cool stuff for Java
  • The Java Collections Framework (Java 1.2)
  • Assertions, amendments to Throwable (Java 1.4)
  • Generics, Annotations and Enum (Java 1.5)
  • try-with-resources and AutoCloseable (Java 1.7)

Structure of the book

• Chapter 2 (Items 1—9)
  • Creating and Destroying Objects (mostly) generic
• Chapter 3 (Items 10—14)
  • Methods Common to All Objects Java-specific
• Chapter 4 (Items 15—25)
  • Classes and Interfaces (mostly) generic
• Chapter 5 (Items 26—33)
  • Generics Java-specific

Structure of the book (continued)

• Chapter 6 (Items 34—41)
  • Enums and Annotations Java-specific
• Chapter 7 (Items 42—48)
  • Lambdas and Streams Java-specific
• Chapter 8 (Items 49—56)
  • Methods generic
• Chapter 9 (Items 57—68)
  • General Programming generic

Structure of the book (continued)

• Chapter 10 (Items 69—77)
  • Exceptions (mostly) generic
• Chapter 11 (Items 78—84)
  • Concurrency (mostly) generic
• Chapter 12 (Items 85—90)
  • Serialization Java-specific

Literature section at PV168 pages

• Code Smells
• Refactoring
• Effective Java
• Design Patterns