Hello Java programmers, if you are looking for the most essential Java libraries to learn and become a more competent Java developer in 2023 then you have come to the right place.

Earlier, I have shared essential Java Frameworks and the best courses to learn Spring Boot, one of the most popular Java frameworks and in this article, I am going to share the most popular and useful Java libraries you can learn to become a better Java programmer in 2023.

One of the traits of a good and experienced Java developer is the extensive knowledge of API, including JDK and third-party libraries. I spent a good deal of time learning API, especially after reading Effective Java 3rd Edition, where Joshua Bloch advised how to use existing APIs for development rather than writing new pieces of code for common stuff.

That advice made sense to me because of the testing exposure 2nd-party libraries get. In this article, I am going to share some of the most useful and essential libraries and APIs that a Java developer should be familiar with.

However, I am not including frameworks, Spring and Hibernate, because they are pretty well known and have specific features.

In general, I am including useful libraries for day-to-day projects, including logging libraries like Log4j, JSON parsing libraries like Jackson, and unit testing APIs like JUnit and Mockito.

If you need to use them in your project, then, you can either include JARs of these libraries in your project’s classpath to start using them or you can use Maven for dependency management.

When you use Maven for dependency management, it will automatically download these libraries, including the libraries they depend on, known as the transitive dependency.

For example, if you download the Spring Framework, it will also download all other JARs on which Spring is dependent, for example, Log4j.

You might not realize, but having the right version of dependent JARs is a big headache. If you have the wrong versions of the JAR, then, you will get the ClassNotFoundException, NoClassDefFoundError, or the UnsupportedClassVersionError in Java. If you have faced them before then you know how painful they are to solve.