Practical Java 8
Lambdas, Streams and new resources
1st Edition
Published on 1. January 2014
136 pages
978-85-66250-58-9 (ISBN)
Description
Are you a programmer fluent in Java? It's time to take the next step! Almost 20 years after it's first version, there is a new Java with important news! Amongst the main new resources, there are the default methods, method references and lambdas. They are simple concepts, but bring important possibilities. In the book we will explore various advancements found in Java 8. Always using practical examples and presenting real usage cases, we migrate the day-to-day legacy code to the new Java 8 functional paradigm. With this triad of concepts, the API managed to evolve in an interesting manner. The java.util.stream and java.util.function packages are deeply explored, presenting simple ways to work with collections and other data structures. Streams and Collectors will be part of your routine and will become as essential as Collections and the java.io currently are to your applications. Lastly, we'll see how the new API java.time comes to change from water to wine the way how we work with dates and times.
More details
Persons
Paulo Silveira, @paulo_caelum, graduated from USP in Computer Science, has over 10 years of software development experience, including jobs at Germany and IBOPE. Currently, coordinates Caelum's summer courses at USP. One of the founders of GUJ.com.br and technical editor for the 'Mundo Java' magazine.
Rodrigo Turini, gratuate in Computer Science, is a developer and instructor at Caelum. He develops web applications in Java and currently focuses his studies on the cloud computing influence as a service.
Rodrigo Turini, gratuate in Computer Science, is a developer and instructor at Caelum. He develops web applications in Java and currently focuses his studies on the cloud computing influence as a service.
Content
- Intro
- Java 8
- Hold your horses!
- Access the code and talk to us!
- Hello Lambda!
- The old way and the new way of doing loops
- Let Lambda in!
- Functional Interfaces
- Another Example: listeners
- Your very own functional interface
- The @FunctionalInterface annotation
- Digging deeper: the first details
- Default Methods
- The forEach method in the Iterable interface
- The Consumer interface doesn't have only one method!
- Another new method in Collection: removelf
- Multiple Inheritance?
- Sorting in Java 8
- Comparators using lambda
- The List.sort method
- Static methods in the Comparator Interface
- Knowing the Comparator.comparing better
- Sorting by score and the autoboxing
- Method References
- Turning all users into moderators
- Comparing in an even lighter way
- Composing comparators
- Referencing instance methods
- Referencing methods that receive arguments
- Referencing constructors
- Other types of references
- Streams and Collectors
- Making the top 10 users with highest scores moderators
- Streams: making the users with a score higher than 100 moderators
- How to get a List back?
- Collectors
- Advanced: why isn't there a toList in Stream?
- Listing only the scores of all users by using map
- InStream and the Streams family
- Optional in java.util
- More operations with Streams
- Sorting a Stream
- Many operations in Stream are lazy!
- what is the advantage of lazy methods?
- Seeing at the pipeline executing with peek
- Reduction operations
- Learning about other Stream methods
- Primitive and infinite streams
- Practicing what we learn with java.nio.file.Files
- FlatMap
- Mapping, partitioning, grouping, and parallelizing
- Collectors generating maps
- groupingBy and partitioningBy
- Running the pipeline in parallel
- Nondeterministic operations and ordered streams
- Enough with Calendar! New date API
- Java.time comes from Joda Time
- Working with dates fluently
- Enums instead of constants
- Formatting in the new date API
- Invalid dates
- Duration and Period
- Differences from Joda Time
- A payment model with Java 8
- A digital goodies store
- Reducing BigDecimal into sums
- Best selling products
- Value generated by product
- What are the products of each customer?
- Which one is our most special client?
- Reports with dates
- Subscription System
- Appendix: more Java 8 with reflection, JVM, APIs, and limitations
- New details in the language
- What is the type of a Lambda expression?
- Inference limitations in Lambda
- End of PermGen
- Reflection: parameter names
