Java Full-Stack Index Q1/2023: JVM Languages

The content of this page is identical throughout Q1/2023 - January, February, and March.

Summary for Q1/2023

• Popularity trend: Java is #1, Kotlin #2, and Scala #3. Java probably wins in job ad mentions where Scala also leads Kotlin. But Kotlin leads Scala in all other categories. Groovy and Clojure have mostly declined for many years. Python and JavaScript beat Java everywhere, but the job ad mentions rankings are unknown.
• On your current project, keep your existing language unless that language is absolutely, really not working out for you.
• If you need to switch languages or are on a new project:
  • Use Scala if you need functional programming.
  • Use Kotlin if you really need a “more modern Java”.
  • Otherwise, use the latest Java LTS version you, your team, and your application can take.

Archive

Table Of Contents

• Summary for Q1/2023
• Archive
• Choices
• Popularity
  • Why Popularity - and How?
  • Employers: Job Ads
  • Developers
    • Students at Udemy
    • Google Searches
    • Questions at Stack Overflow
• Analysis

Choices

Here are the choices in alphabetical order:

• Clojure
• Apache Groovy
• Java
• Kotlin
• Scala

Popularity

Why Popularity - and How?

Picking a popular technology makes our developer life easier: Easier to learn, easier to build, debug & deploy, easier to find jobs/hire, and easier to convince teammates & bosses. Now popularity can make a difference in two situations: When multiple technologies score similarly, we could go for the most popular one. And when a technology is very unpopular, we may not use it.

I measure popularity among employers and developers as the trend between competing technologies. I count mentions in job ads at Indeed for employer popularity. For developer popularity, I use Google searches, Udemy course buyers, and Stack Overflow questions.

Employers: Job Ads

The Indeed job search is active in 62 countries. I picked 59 countries representing 69% of the worldwide GDP in 2022, excluding three countries because English word searches proved ineffective there: China, Japan, and South Korea. It demonstrates the willingness of organizations to pay for technology - the strongest indicator of popularity in my mind. Kotlin is the baseline. Please note that the chart is not proportional, so all languages fit nicely.

This is the first time I exclude China, Japan, and South Korea from the ranking because English word searches proved ineffective there. I adjusted all past numbers as well for this issue, so they are different from past issues. And because of technical difficulties on my end, I don’t have the numbers for October 2022.

I also messed up the counting of Java jobs when battling the fact that searching for “Java” at Indeed also finds ads with “Javascript”. So my Java job numbers have been off since the beginning, and I discarded them. I’ll count Java jobs correctly now — hopefully. Mea culpa!

For comparison, here’s the last chart version with China, Japan, and South Korea from Q4/2022. These are the differences:

• Kotlin has about 75% of Scala’s numbers generally, vs. partially beating Scala before.
• Groovy is about a third higher generally.

Java probably wins, Scala is second, and Kotlin is third. Java probably has the most jobs. I just don’t know how many. Surprisingly, Kotlin only reaches 73% of Scala numbers — and that’s with all the Android developers! Groovy has a quarter of Scala’s numbers, while Clojure has just 4%.

Now let’s look at how the JVM competition does.

This is the first time I exclude China, Japan, and South Korea from the ranking because English word searches proved ineffective there. I adjusted all past numbers as well for this issue, so they are different from past issues. And because of technical difficulties on my end, I don’t have the numbers for October 2022.

For comparison, here’s the one chart with data from China, Japan, and South Korea from Q4/2022. These are the differences:

• Python is 23% lower now.
• JavaScript is 23% lower now.
• C# and C++ are 35% lower now.
• TypeScript is 40% lower now.
• Rust is 10% lower now.
• Go is 84% lower now.

Python wins, JavaScript places second, and C# is third. JavaScript gained on Python while C#, TypeScript, and Go held steady. Rust doubled its share.

Please see here for details, caveats, and adjustments to the job ad mentions.

You can find the detailed search results with links here. They include breakdowns by continents:

Developers

Students at Udemy

Udemy is one of the biggest online learning sites. They publish the number of people who bought a course (beyond a certain threshold, possibly around 100k). This shows how many people evaluate a technology. Kotlin is the baseline.

Java wins by an order of magnitude, Kotlin is second, and Scala is third. Scala is stable against Kotlin, while Kotlin slowly gains on Java. Groovy and Clojure don’t have enough students to cross the display threshold.

Here are the links that show the courses for all and the number of students for some:

• Clojure
• Groovy
• Java
• Kotlin
• Scala

Here are the number of students for languages that compete with the JVM:

Python wins, JavaScript is second, Java third, C# fourth, and Go a distant number five. It’s hard to fathom how popular Python is: It has 38 million students — almost three times as many as Java! That’s more than there are professional developers worldwide, estimated at 27 million in 2021. JavaScript leads Java by 10%. Java’s old rival C# sits at 41% of Java. Go, the new kid on the block, has just 7% of Java’s numbers. All competitors grow slightly faster than Java.

Here are the links that show the courses and number of students for all:

• C#
• Go
• JavaScript
• Python

Google Searches

Google Trends demonstrates the initial interest in a technology over time:

Google changed its measurement algorithms on January 1, 2016, and January 1, 2022. That caused spikes for all values, especially in 2022.

This link produces the chart above.

Even at 1/7 of its peak interest in 2004, Java still beats Kotlin 14:1.

To get a better picture of the Java alternatives, here they are without Java:

This link produces the chart above.

Among the Java challengers, Kotlin wins, Scala is second, Groovy is third, and Clojure is last. We can see the fall of Scala and the rise of Kotlin, both starting about six years ago. Kotlin peaked last April and has declined since then, leading Scala 3:1. Scala has also shrunk most of 2022. Groovy has declined for four years, while Clojure has for 6.5 years.

Here are searches for the languages that compete with the JVM:

This link produces the chart above.

Here are the JVM competitors over the last three years:

This link produces the chart above.

Python wins, JavaScript is second, Java is third, C# is fourth, and Go is fifth. Python is 36% more popular than JavaScript, which leads Java by 6%. Python and JavaScript are the only languages that have grown significantly in the last three years. C# has only 43% of Java’s search volume, while Go only has 24%.

Questions at Stack Overflow

Stack Overflow Trends shows which percentage of questions at Stack Overflow has a particular technology tag. It is a proxy for using a technology during evaluation and productive use. “More questions = better” to me.

This link produces the chart above.

Java wins, Kotlin is second, and Scala is third. Java has lost 54% of its questions in the last seven years. Kotlin grew only slightly in 2022 and has a quarter of Java’s questions. Scala lost two-thirds of its question volume over the previous six years. Groovy and Clojure have hovered just above zero for as long as Stack Overflow has existed.

Here are the shares of questions for the languages that compete with the JVM:

This link produces the chart above.

Python wins, JavaScript is second, Java third, C# fourth, TypeScript fifth, and Go sixth. Python’s incredible popularity shows again: After a ten-year rise, it captures one in six questions on Stack Overflow! But it zig-zagged between 16% and 17% for the last 2.5 years, sitting at a near-peak value of 16.8%. JavaScript has declined for two years but still has 63% of Python’s numbers. After falling for eight years, Java only has 48% of the questions JavaScript has. And after dropping for 12 years, C# has risen again in 2022 and is gunning for Java. After a seven-year rise, TypeScript just hit its all-time high and sits at 60% of C#’s questions. Go just peaked as well at a seventh of Java’s numbers.

Analysis

• Usage of Java still dominates its alternatives, often by an order of magnitude.
• The evolution speed of the Java language has increased. So even staying with the incumbent Java makes life for us developers easier.
• If Oracle gets its will, then we’ll get a new Java LTS every two years instead of every three years. This would speed up the delivery of Java language improvements.
• Kotlin is the best Java alternative. I believe that Kotlin’s rise in popularity is partly fueled by its status as the default language for Android development.
• Scala lost its position as the #2 JVM language. In job ads, it’s ahead of Kotlin, especially in places like North America (where it leads Kotlin 2:1). But Google searches and Stack Overflow questions trend towards Kotlin. That’s why Scala is #3 for me.
• There’s one overwriting factor that requires Scala: functional programming. If that’s your need, you have to use Scala on the JVM.
• Groovy is a has-been on the JVM: Kotlin stole its place of “better Java”, while Grails (Ruby-on-Rails with Groovy on the JVM) has fallen out of favor. I know that the Tiobe Index places Groovy way ahead of other JVM language alternatives to Java, but I think that view is somewhat exclusive to Tiobe.
• Clojure fills the niche of “Lisp on the JVM”.

Here’s my recommendation:

• On your current project, keep your existing language unless that language is absolutely, really not working out for you.
• If you need to switch languages or are on a new project:
  • Use Scala if you need functional programming.
  • Use Kotlin if you really need a “more modern Java”.
  • Otherwise, use the latest Java LTS version you, your team, and your application can stomach.