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

jimschubert
In Chapter 3, the source for index introduces Config on page 31, followed by more code including tests; Config isn’t introduced until pag...
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
edruder
I thought that there might be interest in using the book with Rails 6.1 and Ruby 2.7.2. I’ll note what I needed to do differently here. ...
New
HarryDeveloper
Hi @venkats, It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
leonW
I ran this command after installing the sample application: $ cards add do something --owner Brian And got a file not found error: Fil...
New
fynn
This is as much a suggestion as a question, as a note for others. Locally the SGP30 wasn’t available, so I ordered a SGP40. On page 53, ...
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
New
EdBorn
Title: Agile Web Development with Rails 7: (page 70) I am running windows 11 pro with rails 7.0.3 and ruby 3.1.2p20 (2022-04-12 revision...
New
dachristenson
@mfazio23 Android Studio will not accept anything I do when trying to use the Transformations class, as described on pp. 140-141. Googl...
New

Other popular topics Top

PragmaticBookshelf
Stop developing web apps with yesterday’s tools. Today, developers are increasingly adopting Clojure as a web-development platform. See f...
New
PragmaticBookshelf
Brace yourself for a fun challenge: build a photorealistic 3D renderer from scratch! In just a couple of weeks, build a ray tracer that r...
New
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
Rainer
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
New
AstonJ
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first: asdf plugin-upd...
New
PragmaticBookshelf
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
New
husaindevelop
Inside our android webview app, we are trying to paste the copied content from another app eg (notes) using navigator.clipboard.readtext ...
New
AnfaengerAlex
Hello, I’m a beginner in Android development and I’m facing an issue with my project setup. In my build.gradle.kts file, I have the foll...
New

Latest in Functional Programming in Java, Second Edition

Functional Programming in Java, Second Edition Portal

Sub Categories: