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As Java developers working with a language that’s both mature yet highly evolving, we’re faced with a constant dilemma whenever we write new code – go with the hot new technology that everyone is talking about, or stick with a tried-and-true library?

Since a very large part of Java applications are commercial in nature, it can sometimes be hard to separate the buzz around a new framework with the number of projects actually putting it to use. This is important, as the community of users and contributors around a framework is one of the strongest factors in determining its continuous success and development.

We decided to use a data based approach to get more insight into this, by analyzing which Java projects developers are actually using on the world’s largest open repository for Java projects – GitHub.

In our previous post we presented the main results of our GitHub research project and the top 100 libraries for JavaScript, Ruby and Java. Now let’s dive into the data, analyzing Java in particular.

The Approach

To generate our dataset we queried 10,000 Java projects, with a bias towards the ones most favorited by the community, as a strong qualifying indicator towards their relative importance. We used the pom.xml, which is used by the vast majority of Java projects on GH, to define dependencies. We then analyzed and grouped those into categories. The results were really interesting.

The Results

The full list – Top 100 libraries for JavaScript, Ruby and Java

Logging. The most popular Java library is slf4j – the logging facade framework, with 3,068 entries. It seems that Java GH developers have fully embraced a decoupled approach towards their logging engine, and have standardized on slf4j to do so.

Since slf4j isn’t a logging engine by itself, it’s also useful to see the top logging engines being used. It looks like the “winner” here is log4j – 891 projects are using it. Next in line is Logback, with 340 projects. While very respectable, this number still represents less than half of the projects using log4j. sfl4j’s simple logging implementation comes in third at 174 projects.

The most popular Java library today is slf4j – used by 30.7% of the 10,000 projects (Tweet this)

Spring. While Spring may be perceived by some as a more mature and less “hip” framework, it still sees tremendous usage, placing 15 libraries in the top 100. Since Spring is an umbrella framework, it’s interesting to see which of its components are being used the most. Spring-test is the most used part of the framework (after the core library) with 376 entries. It’s followed by web-mvc for designing robust web applications with 277 entries. After web functionality, we see web-orm with 218 entries, highlighting Spring’s key use case for building a DB backed Java web application.

TDD. Right there with Spring at the top is JUnit with 3,068 entries. This really shows the profound effect that Test Driven Development has had on the Java landscape. It seems that if you’re a Java developer posting your code, unit tests today are an absolute requirement. It’s also worthwhile noting that while JUnit is not alone in this space (TestNG, the 2nd most popular testing framework, has 331 entries) it is by far the most dominant.

Mockito, a popular framework for mock based testing, has also gained wide appeal with 413 entries. EasyMock, another mocking framework, comes 2nd in this category with 231 project entries.

Google’s Guava framework is becoming mainstream – 4.8% of 10,000 Java GitHub projects are using it (Tweet this)

Apache Commons. Having looked at Spring, it’s important we don’t neglect Apache Commons, one of the most fundamental set of libraries within the language. Commons-io and Commons-lang are right there in the top 10 with 519 and 504 entries respectively, showing their strong prevalence.

As a whole Apache Commons have 13 libraries in the top 100. Google’s Guava framework, which itself provides language utils (some similar to those found in Commons) is also doing very well with 483 entries, marking it as another key Java building block.

Sql & NoSql. With NoSql and Big data being all the buzz these last couple of years (some for good reasons), it’s worthwhile looking at the actual usage numbers for both relational and NoSql technologies. The most popular Sql DB out there is MySql with 225 entries. Hibernate ORM, while not a DB in itself, is also fairly popular with 181 entries. This is one area that we need to keep in mind that as GH is an open source repository, we might see a somewhat stronger bias towards commercial DBs such as Oracle’s in a closed source dataset.

Justifying the buzz: Hadoop is more popular in Java GitHub projects than Postgre SQL (Tweet this)

Hadoop is also doing very well with 168 entries, showing that the buzz is justified when looking at its actual usage data. To put in perspective, it has more entries than Postgre SQL (with 121 entries), one of the most mature relational open source DBs out there.

ElasticSearch, another Big data technology, is also on the board with 110 project entries. It’s surprising to note that sqlite, which has 1,085 entries in Ruby, isn’t in the Java top 100.

Android. For mobile developers on GH we see 228 project entries consuming Android via Maven. While this can signify that not a lot of mobile projects are placed on GH, it’s still a strong indicator that Java remains a very strong server side language.

Surprised by some of the results? We know we were with some of them. Take a look at the full list of the top 100 Java libraries on GitHub below, and let us know what you think in the comments section. We’d love to hear your thoughts and questions.

We Analyzed 30,000 GitHub Projects – Here Are The Top 100 Libraries in Java, JS and Ruby – read more