dtonhofer

dtonhofer

Functional Programming in Java, Second Edition: p. 55 "Compare.java" can be further simplified

On page 55, we see Compare.java

final Function<Person, String> byName = person -> person.getName();
people.stream()
   .sorted(comparing(byName));

However, this can be further simplified to:

people.stream()
   .sorted(comparing(Person::getName));

On the same page, more from Compare.java:

final Function<Person, Integer> byAge = person -> person.getAge();
final Function<Person, String> byTheirName = person -> person.getName();
printPeople("Sorted in ascending order by age, then name: ",
                people.stream()
                        .sorted(comparing(byAge).thenComparing(byTheirName))
                        .collect(toList());

which can be simplified similarly to:

printPeople("Sorted in ascending order by age, then name: ",
                people.stream()
                        sorted(comparing(Person::getAge).thenComparing(Person::getName))
                        .collect(toList());

but which would be even better by separating the list generation and output tasks:

List<Person> asc =
                people.stream()
                        .sorted(comparing(Person::getAge).thenComparing(Person::getName))
                        .collect(toList());
        printPeople("Sorted in ascending order by age, then name: ", asc);

…all according to the JavaDoc for Comparator:

P.S.

Would it be clearer to explicitly write the class from which comparing() comes instead of assuming it has been imported statically? Like this:

people.stream()
   .sorted(Comparator.comparing(Person::getName));

instaed of

people.stream()
   .sorted(comparing(Person::getName));

Note that the collect()call

people.stream()
   .sorted(comparing(byAge).thenComparing(byTheirName))
   .collect(toList()));

…also assume a statically imported toList(). On the other hand, compare/fpij/OlderThan20.java on page 58 is explicit:

List<Person> olderThan20 =
   people.stream()
      .filter(person -> person.getAge() > 20)
      .collect(Collectors.toList());

Where Next?

Popular Pragmatic Bookshelf topics Top

jon
Some minor things in the paper edition that says “3 2020” on the title page verso, not mentioned in the book’s errata online: p. 186 But...
New
iPaul
page 37 ANTLRInputStream input = new ANTLRInputStream(is); as of ANTLR 4 .8 should be: CharStream stream = CharStreams.fromStream(i...
New
telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
New
yulkin
your book suggests to use Image.toByteData() to convert image to bytes, however I get the following error: "the getter ‘toByteData’ isn’t...
New
gilesdotcodes
In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...
New
jgchristopher
“The ProductLive.Index template calls a helper function, live_component/3, that in turn calls on the modal component. ” Excerpt From: Br...
New
nicoatridge
Hi, I have just acquired Michael Fazio’s “Kotlin and Android Development” to learn about game programming for Android. I have a game in p...
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “&gt;...
New
Keton
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New
gorkaio
root_layout: {PentoWeb.LayoutView, :root}, This results in the following following error: no “root” html template defined for PentoWeb...
New

Other popular topics Top

DevotionGeo
I know that these benchmarks might not be the exact picture of real-world scenario, but still I expect a Rust web framework performing a ...
New
AstonJ
Or looking forward to? :nerd_face:
483 11975 256
New
brentjanderson
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
New
AstonJ
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
First poster: joeb
The File System Access API with Origin Private File System. WebKit supports new API that makes it possible for web apps to create, open,...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
PragmaticBookshelf
Fight complexity and reclaim the original spirit of agility by learning to simplify how you develop software. The result: a more humane a...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: