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

telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
New
jesse050717
Title: Web Development with Clojure, Third Edition, pg 116 Hi - I just started chapter 5 and I am stuck on page 116 while trying to star...
New
raul
Hi Travis! Thank you for the cool book! :slight_smile: I made a list of issues and thought I could post them chapter by chapter. I’m rev...
New
raul
Page 28: It implements io.ReaderAt on the store type. Sorry if it’s a dumb question but was the io.ReaderAt supposed to be io.ReadAt? ...
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
adamwoolhether
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
jonmac
The allprojects block listed on page 245 produces the following error when syncing gradle: “org.gradle.api.GradleScriptException: A prob...
New
creminology
Skimming ahead, much of the following is explained in Chapter 3, but new readers (like me!) will hit a roadblock in Chapter 2 with their ...
New
tkhobbes
After some hassle, I was able to finally run bin/setup, now I have started the rails server but I get this error message right when I vis...
New
andreheijstek
After running /bin/setup, the first error was: The foreman' command exists in these Ruby versions: That was easy to fix: gem install fore...
New

Other popular topics Top

Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1044 20579 391
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
AstonJ
SpaceVim seems to be gaining in features and popularity and I just wondered how it compares with SpaceMacs in 2020 - anyone have any thou...
New
DevotionGeo
I know that -t flag is used along with -i flag for getting an interactive shell. But I cannot digest what the man page for docker run com...
New
AstonJ
Thanks to @foxtrottwist’s and @Tomas’s posts in this thread: Poll: Which code editor do you use? I bought Onivim! :nerd_face: https://on...
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
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
NewsBot
Node.js v22.14.0 has been released. Link: Release 2025-02-11, Version 22.14.0 'Jod' (LTS), @aduh95 · nodejs/node · GitHub
New
Margaret
Ask Me Anything with Mark Volkmann @mvolkmann On February 24 and 25, we are giving you a chance to ask questions of PragProg author M...
New
PragmaticBookshelf
A concise guide to MySQL 9 database administration, covering fundamental concepts, techniques, and best practices. Neil Smyth MySQL...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: