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Questions answered in this episode: "How do I learn Docker, Kubernetes, Spark, and NodeJS as a Senior Java dev?"

Learn more about the best Java unit testing frameworks. Unit testing is an important skill for programmers. With that said, what are the best frameworks you can use to write great unit tests in Java? You may also like: 8 Benefits of Unit ... [More] Testing What We Will Learn What are the best Java unit testing frameworks? What is JUnit? How do you use JUnit for unit testing? What is Mockito? What is mocking? How do you write unit tests with Junit, Mockito, AssertJ, and other frameworks? What is the best Java unit testing framework for writing great asserts? The Base Unit Testing Framework — JUnit/TestNG Whenever you write a unit test, you execute the code and then check its output. You need a basic framework in place to run a large number of tests in a similar manner. [Less]

Folding things can be fun! Introduction In this post, we will discuss the concept of fold in functional programming: fold functions are used to reduce a data structure containing multiple values into a single one. Associated to the idea ... [More] of fold are the concepts of... recursion: via recursion, fold traverses the different elements of the data structure. summarisation: the data structure with all its elements is reduced to a single value You may also like: 10 Amazing Scala Collection Functions In the following example, the class Rectangle can be reduced to a single value representing its area. However, it is not 'foldable' in the sense that there is no recursion involved. [Less]

Combining predicates in Java brings developers lots of joy. In Java, we can use a Predicate to test if something is true or false. This is especially useful when we use the filter method of the Java Stream API. You may also like: Towards ... [More] More Functional Java Using Lambdas as Predicates We can use lambda expressions to define our Predicate or implement the Predicate interface. If we want to combine different Predicate objects, we can use the or, and, and negate methods of the Predicate interfaces. These are default methods of the interface and will return a new Predicate. [Less]

Stay hip with JHipster for your Java and Spring Boot apps If you’re confused by how OAuth 2.0 and OpenID Connect (OIDC) work together, please see What the Heck is OAuth? In short, OIDC is a thin layer on top of OAuth 2.0 that adds identity. The ... [More] Java world has been very busy lately, especially with all the major Java versions releasing every six months. This honestly can be a lot to keep up with. I was using Java 8 until I was introduced to Spring Boot 2.1. [Less]

Out with the old, in with Spring Boot 2 Recently, we decided to monitor the metrics of legacy Spring applications we were running on our production systems. While searching around, I realized that a nice way to not reinvent the wheel was to ... [More] integrate my app with the Spring Boot Actuator. By using the actuator, we have many tools like Grafana and Prometheus for easily monitoring our applications. However, in order to integrate such a legacy Spring application with the Spring Boot Actuator, you need to make it Spring-Boot-ready first. You may also like:  How to Deal With Legacy Code Since Spring Boot 1.5 reached the end of its life at the beginning of August, I decided to move to Spring Boot 2 and start playing with it. [Less]

Poor code performance is trash. In this article, we have attempted to answer the most common questions around System.gc() API call. We hope it may be of help. You may also like: Java Garbage Collection What Is System.gc()? ... [More] System.gc() is an API provided in Java, Android, C#, and many other popular languages. When invoked, it will make its best effort to clear an accumulated unreferenced object (i.e. garbage) from memory. [Less]

Use JUnit to test your Java applications What’s a good way to show that you care about your code? Using unit and integration tests to ensure your code is up to par. You may also like: JUnit Tutorial: Setting Up, Writing, and Running Java ... [More] Unit Tests Recently, I worked to upgrade JHipster, so it can support the latest release of Spring Security. OAuth 2.0 and OIDC were added as first-class citizens to Spring Security 5.1, which allows you to configure with its wonderful DSL (method chaining or builder pattern). This latest addition to Spring Security makes OAuth great! [Less]

At Devoxx BE 2018, I was interviewed by Yolande Poirier on the difference is between Java EE, Jakarta EE, and MicroProfile, and what to choose for Enterprise Java projects. Here are my thoughts on the topic as well as recommendations. During the ... [More] 7-minute conversation, we also discussed what enterprise projects could build their enterprise applications on. Check it out! [Less]

Your Java code just needs a little magic In the previous article Everything You Need to Know About Java Serialization, we discussed how serializability of a class is enabled by implementing the Serializable interface. If our class does not ... [More] implement Serializable interface, or if it is having a reference to a non-Serializable class, then the JVM will throw NotSerializableException. You may also like: Serialization and De-Serialization in Java All subtypes of a serializable class are, themselves, serializable, and the Externalizable interface also extends Serializable. So even if we customize our serialization process using Externalizable, our class is still a Serializable. [Less]