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

abtin
page 20: … protoc command… I had to additionally run the following go get commands in order to be able to compile protobuf code using go...
New
simonpeter
When I try the command to create a pair of migration files I get an error. user=&gt; (create-migration "guestbook") Execution error (Ill...
New
herminiotorres
Hi! I know not the intentions behind this narrative when called, on page XI: mount() |&gt; handle_event() |&gt; render() but the correc...
New
joepstender
The generated iex result below should list products instead of product for the metadata. (page 67) iex&gt; product = %Product{} %Pento....
New
hgkjshegfskef
The test is as follows: Scenario: Intersecting a scaled sphere with a ray Given r ← ray(point(0, 0, -5), vector(0, 0, 1)) And s ← sphere...
New
jonmac
The allprojects block listed on page 245 produces the following error when syncing gradle: “org.gradle.api.GradleScriptException: A prob...
New
kolossal
Hi, I need some help, I’m new to rust and was learning through your book. but I got stuck at the last stage of distribution. Whenever I t...
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
redconfetti
Docker-Machine became part of the Docker Toolbox, which was deprecated in 2020, long after Docker Desktop supported Docker Engine nativel...
New
New

Other popular topics Top

New
AstonJ
We have a thread about the keyboards we have, but what about nice keyboards we come across that we want? If you have seen any that look n...
New
New
Exadra37
Oh just spent so much time on this to discover now that RancherOS is in end of life but Rancher is refusing to mark the Github repo as su...
New
PragmaticBookshelf
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
New
PragmaticBookshelf
Use WebRTC to build web applications that stream media and data in real time directly from one user to another, all in the browser. ...
New
New
New
New
sir.laksmana_wenk
I’m able to do the “artistic” part of game-development; character designing/modeling, music, environment modeling, etc. However, I don’t...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: