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

iPaul
page 37 ANTLRInputStream input = new ANTLRInputStream(is); as of ANTLR 4 .8 should be: CharStream stream = CharStreams.fromStream(i...
New
Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
mikecargal
Title: Hands-on Rust: question about get_component (page 295) (feel free to respond. “You dug you’re own hole… good luck”) I have somet...
New
alanq
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
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
jskubick
I think I might have found a problem involving SwitchCompat, thumbTint, and trackTint. As entered, the SwitchCompat changes color to hol...
New
jskubick
I found an issue in Chapter 7 regarding android:backgroundTint vs app:backgroundTint. How to replicate: load chapter-7 from zipfile i...
New
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
a.zampa
@mfazio23 I’m following the indications of the book and arriver ad chapter 10, but the app cannot be compiled due to an error in the Bas...
New
dtonhofer
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
New

Other popular topics Top

PragmaticBookshelf
Ruby, Io, Prolog, Scala, Erlang, Clojure, Haskell. With Seven Languages in Seven Weeks, by Bruce A. Tate, you’ll go beyond the syntax—and...
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
AstonJ
You might be thinking we should just ask who’s not using VSCode :joy: however there are some new additions in the space that might give V...
New
PragmaticBookshelf
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
New
New
PragmaticBookshelf
Author Spotlight Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
AstonJ
If you want a quick and easy way to block any website on your Mac using Little Snitch simply… File &gt; New Rule: And select Deny, O...
New
New
PragmaticBookshelf
Explore the power of Ash Framework by modeling and building the domain for a real-world web application. Rebecca Le @sevenseacat and ...
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: