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
As per the title, thanks.
New
Title: Web Development with Clojure, Third Edition - migrations/create not working: p159
When I execute the command:
user=> (create-...
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 @venkats,
It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
The generated iex result below should list products instead of product for the metadata. (page 67)
iex> product = %Product{}
%Pento....
New
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
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
Title: Build a Weather Station with Elixir and Nerves: Problem connecting to Postgres with Grafana on (page 64)
If you follow the defau...
New
Hi, I’m working on the Chapter 8 of the book.
After I add add the point_offset, I’m still able to see acne:
In the image above, I re...
New
Getting an error when installing the dependencies at the start of this chapter:
could not compile dependency :exla, "mix compile" failed...
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
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
Write Elixir tests that you can be proud of. Dive into Elixir’s test philosophy and gain mastery over the terminology and concepts that u...
New
You might be thinking we should just ask who’s not using VSCode :joy: however there are some new additions in the space that might give V...
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
Biggest jackpot ever apparently! :upside_down_face:
I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
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
A concise guide to MySQL 9 database administration, covering fundamental concepts, techniques, and best practices.
Neil Smyth
MySQL...
New
Ok, well here are some thoughts and opinions on some of the ergonomic keyboards I have, I guess like mini review of each that I use enoug...
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
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /centos
- /deepseek
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /deno
- /django
- /kubuntu
- /arch-linux
- /nodejs
- /spring
- /ubuntu
- /revery
- /manjaro
- /lua
- /julia
- /diversity
- /markdown
- /slackware









