dtonhofer
Functional Programming in Java, Second Edition: Code reorganization into JUnit tests rather than individual main-adorned classes
This may be too extensive to change, but I would like to see the code example not as a series of classes with main() but as JUnit test classes.
One can then have all the code for one chapter in single class, and execute the individual methods, each corresponding to an example, directly from the IDE, without messing around with calling this or that main().
I suppose everyone knowledgeable of Java knows about JUnit at this point.
For example, for a part of chapter 3:
import org.junit.jupiter.api.Test;
import java.io.File;
import java.io.IOException;
import java.nio.file.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static java.util.stream.Collectors.toList;
public class MyTest {
private final static String theDir = "foo";
// "Listing Select Files in a Directory", p.61
@Test
public void listSelectFilesTheHardWay() {
final String[] files =
new File(theDir).list(new java.io.FilenameFilter() {
public boolean accept(final File _dir, final String name) {
return name.endsWith(".java");
}
});
String res =
(files == null) ?
("Looks like '" + theDir + "' is not a directory") :
(Arrays.stream(files).collect(Collectors.joining("\n")));
System.out.println(res);
}
// "Listing Select Files in a Directory", p.61
@Test
public void listSelectFilesTheGoodWay() {
try {
Files.newDirectoryStream(
Paths.get(theDir), path -> path.toString().endsWith(".java"))
.forEach(System.out::println);
} catch (IOException ex) {
System.out.println("Looks like '" + theDir + "' is not a directory, or something");
}
}
}
If one loads this into the IDE, one just needs to hit the green arrows next to the @Test annotations for great results.
P.S.
I just noticed that an actual main() makes an appearance on p.69, like a blast from the past. It really would look better as a test case.
Popular Pragmatic Bookshelf topics
Working through the steps (checking that the Info,plist matches exactly), run the demo game and what appears is grey but does not fill th...
New
Hello Brian,
I have some problems with running the code in your book. I like the style of the book very much and I have learnt a lot as...
New
When I try the command to create a pair of migration files I get an error.
user=> (create-migration "guestbook")
Execution error (Ill...
New
I can’t setup the Rails source code. This happens in a working directory containing multiple (postgres) Rails apps.
With:
ruby-3.0.0
s...
New
Hi! I know not the intentions behind this narrative when called, on page XI:
mount() |> handle_event() |> render()
but the correc...
New
AWDWR 7, page 152, page 153:
Hello everyone,
I’m a little bit lost on the hotwire part. I didn’t fully understand it.
On page 152 @rub...
New
Book: Programming Phoenix LiveView, page 142 (157/378), file lib/pento_web/live/product_live/form_component.ex, in the function below:
d...
New
@mfazio23
I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
New
Is there any plan for volume 2? :slight_smile:
New
I’ve got to the end of Ch. 11, and the app runs, with all tabs displaying what they should – at first. After switching around between St...
New
Other popular topics
Take your Go skills to the next level by learning how to design, develop, and deploy a distributed service. Start from the bare essential...
New
Andy and Dave wrote this influential, classic book to help their clients create better software and rediscover the joy of coding. Almost ...
New
Learn from the award-winning programming series that inspired the Elixir language, and go on a step-by-step journey through the most impo...
New
New
No chair. I have a standing desk.
This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
Just done a fresh install of macOS Big Sur and on installing Erlang I am getting:
asdf install erlang 23.1.2
Configure failed.
checking ...
New
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
Author Spotlight
Erin Dees
@undees
Welcome to our new author spotlight! We had the pleasure of chatting with Erin Dees, co-author of ...
New
I have always used antique keyboards like Cherry MX 1800 or Cherry MX 8100 and almost always have modified the switches in some way, like...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /java
- /emacs
- /haskell
- /svelte
- /typescript
- /onivim
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /deepseek
- /zig
- /centos
- /php
- /scala
- /react-native
- /lisp
- /textmate
- /sublime-text
- /nixos
- /debian
- /agda
- /deno
- /django
- /kubuntu
- /arch-linux
- /nodejs
- /spring
- /ubuntu
- /revery
- /manjaro
- /diversity
- /julia
- /lua
- /markdown
- /slackware









