dtonhofer
Functional Programming in Java, Second Edition: p.90 CalculateNAVTest erroneous
On page 90, CalculateNAVTest.java:
public class CalculateNAVTest {
@Test
public void computeStockWorth() {
final CalculateNAV calculateNAV = new CalculateNAV(ticker -> new BigDecimal("6.01"));
BigDecimal expected = new BigDecimal("6010.00");
assertEquals(0, calculateNAV.computeStockWorth("GOOG", 1000).compareTo(expected), 0.001);
}
The assertEquals() makes no sense.
It runs BigDecimal.compare( new BigDecimal("6010") , new BigDecimal("6010.00") ) which is either -1, 0 or +1, and compares it with 0 with an irrelevant precision of 0.001.
What we want is:
public class CalculateNAVTest {
@Test
public void computeStockWorth() {
final CalculateNAV calculateNAV = new CalculateNAV(ticker -> new BigDecimal("6.01"));
BigDecimal expected = new BigDecimal("6010.00");
BigDecimal actual = calculateNAV.computeStockWorth("GOOG", 1000);
BigDecimal delta = actual.subtract(expected);
assertEquals(delta.doubleValue(), 0, 0.001);
}
JavaDoc for BigDecimal.compare():
Marked As Solved
venkats
Author of Programming Kotlin, Rediscovering JavaScript (and 6 other titles)
Very good catch. Fixed. Thank you.
1
Popular Pragmatic Bookshelf topics
The following is cross-posted from the original Ray Tracer Challenge forum, from a post by garfieldnate. I’m cross-posting it so that the...
New
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
Hello! On page xix of the preface, it says there is a community forum "… for help if your’re stuck on one of the exercises in this book… ...
New
Hello! Thanks for the great book.
I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
@noelrappin
Running the webpack dev server, I receive the following warning:
ERROR in tsconfig.json
TS18003: No inputs were found in c...
New
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
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
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
Hi,
I am getting an error I cannot figure out on my test.
I have what I think is the exact code from the book, other than I changed “us...
New
I got this error when executing the plot files on macOS Ventura 13.0.1 with Python 3.10.8 and matplotlib 3.6.1:
programming_ML/code/03_...
New
Other popular topics
Reading something? Working on something? Planning something? Changing jobs even!?
If you’re up for sharing, please let us know what you’...
New
A thread that every forum needs!
Simply post a link to a track on YouTube (or SoundCloud or Vimeo amongst others!) on a separate line an...
New
Algorithms and data structures are much more than abstract concepts. Mastering them enables you to write code that runs faster and more e...
New
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
Which, if any, games do you play? On what platform?
I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
There’s a whole world of custom keycaps out there that I didn’t know existed!
Check out all of our Keycaps threads here:
https://forum....
New
Create efficient, elegant software tests in pytest, Python's most powerful testing framework.
Brian Okken @brianokken
Edited by Kat...
New
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
If you’re getting errors like this:
psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New
This is cool!
DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON
We just witnessed something incredible: the largest open-s...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /emacs
- /java
- /haskell
- /svelte
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /deepseek
- /centos
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /revery
- /ubuntu
- /manjaro
- /spring
- /lua
- /diversity
- /julia
- /markdown
- /c








