alvin alexander

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A Scala “file find” utility

By Alvin Alexander. Last updated: November 21 2019

I wanted some specific features in a “find” utility, and when I couldn’t figure out how to get them with combinations of find, awk, and other Unix commands, I wrote what I wanted in Scala. Those features are (a) showing matching filenames, (b) showing the line that matches my search pattern, and underlining the pattern in the output, (c) showing the line numbers of the matches, and (d) showing an optional number of lines from the file before and after each match.

Some RxJava example source code (Hackers at Cambridge tutorials)

By Alvin Alexander. Last updated: March 3 2019

I recently watched the three Hackers at Cambridge Introduction to RxJava videos, and coded along with them. If you’re interested in some example RxJava code, here’s what I typed in.

The first thing you do is create a new Gradle/Java project with these commands:

mkdir MyProject
cd MyProject
gradle init --type java-application

With that project created you can begin creating some Java/RxJava code.

Show me your flowcharts and conceal your tables ...

By Alvin Alexander. Last updated: October 20 2017

“Show me your flowcharts (source code), and conceal your tables (domain model), and I shall continue to be mystified; show me your tables (domain model) and I won’t usually need your flowcharts (source code): they’ll be obvious.”

~ Fred Brooks, “The Mythical Man Month”

(text in parentheses added by me)

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A look at how the Scala `lazy val` syntax gets converted into Java code (bytecode)

By Alvin Alexander. Last updated: March 22 2019

Table of Contents

  1. A little `lazy val` conversion example
  2. A second `lazy val` conversion example
  3. One more `lazy val` conversion example
  4. The end
Table of Contents1 - A little `lazy val` conversion example2 - A second `lazy val` conversion example3 - One more `lazy val` conversion example4 - The end

I don’t have any major conclusions to share in this blog post, but ... what I was curious about is how Scala implements “lazy val” fields. That is, when the Scala code I write is translated into a .class file and bytecode that a JVM can understand, what does that resulting code look like?

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