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Detecting If a Spring Transaction Is Active
1. Overview Detecting transactions could be useful for audit purposes or for dealing with a complex code base where good transaction conventions weren't implemented. In this brief tutorial, we'll go...
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Finding a Free Port in Java
1. Overview When starting a socket server in our Java application, the java.net API requires us to specify a free port number to listen on. The port number is required so that the TCP layer can...
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Getting Database URL From JDBC Connection Object
1. Overview In this quick tutorial, we'll discuss how we can get the database URL from a JDBC Connection object. 2. Example Class To demonstrate this, we'll create a DBConfiguration class with a method...
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Apache Spark: Differences between Dataframes, Datasets and RDDs
1. Overview Apache Spark is a fast, distributed data processing system. It does in-memory data processing and uses in-memory caching and optimized execution resulting in fast performance. It provides...
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Guide to Jenkins Parameterized Builds
1. Introduction Jenkins is one of the most popular CI/CD tools in use today. It allows us to automate every aspect of the software lifecycle, from building all the way to deploying. In this tutorial,...
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Object States in Hibernate’s Session
1. Introduction Hibernate is a convenient framework for managing persistent data, but understanding how it works internally can be tricky at times. In this tutorial, we'll learn about object states and...
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Constants in Java: Patterns and Anti-Patterns
1. Introduction In this article, we're going to learn about using constants in Java with a focus on common patterns and anti-patterns. We'll start with some basic conventions for defining constants....
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Performance of removeAll() in a HashSet
1. Overview HashSet is a collection for storing unique elements. In this tutorial, we'll discuss the performance of the removeAll() method in the java.util.HashSet class. 2. HashSet.removeAll() The...
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How to Import a .cer Certificate Into a Java KeyStore
1. Overview A KeyStore, as the name suggests, is basically a repository of certificates, public and private keys. Moreover, JDK distributions are shipped with an executable to help manage them, the...
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Java Weekly, Issue 356
1. Spring and Java >> JEP proposed to target JDK 16: Unix-Domain Socket Channels [mail.openjdk.java.net] More channels for NIO: Java 16 will support Unix domain sockets as part of its NIO...
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Introduction to Netflix Mantis
1. Overview In this article, we'll take a look at the Mantis platform developed by Netflix. We'll explore the main Mantis concepts by creating, running, and investigating a stream processing job. 2....
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Accessing Keycloak Endpoints Using Postman
1. Introduction In this article, we start with a quick review of OAuth 2.0, OpenID, and Keycloak. Afterward, we'll learn about the Keycloak REST APIs and how to call them in Postman. 2. OAuth 2.0 OAuth...
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Get Names of Classes Inside a JAR File
1. Overview Most Java libraries are available as JAR files. In this tutorial, we'll address how to get names of classes inside a given JAR file from the command line and from a Java program. Then,...
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Retrofit 2 – Dynamic URL
1. Overview In this short tutorial, we'll learn how to create a dynamic URL in Retrofit2. 2. @Url Annotation There are cases when we need to use a dynamic URL in our application during runtime. Version...
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Set JWT with Spring Boot and Swagger UI
1. Introduction In this short tutorial, we're going to see how to configure Swagger UI to include a JSON Web Token (JWT) when it calls our API. 2. Maven Dependencies In this example, we'll be using...
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Java Weekly, Issue 357
1. Spring and Java >> The JPA and Hibernate first-level cache [vladmihalcea.com] On the benefits of the first-level cache in JPA/Hibernate: write-behind cache, batching, and application-level...
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Dependency Management in Gradle
1. Overview In this tutorial, we'll look at declaring dependencies in a Gradle build script. For our examples, we'll be using Gradle 6.7. 2. Typical Structure Let's start with a simple Gradle script...
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Apache Commons Collections vs Google Guava
1. Overview In this tutorial, we'll compare two Java-based open source libraries: Apache Commons and Google Guava. Both libraries have a rich feature set with lots of utility APIs majorly in the...
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Storing Files Indexed by a Database
1. Overview When we are building some sort of content management solution, we need to solve two problems. We need a place to store the files themselves, and we need some sort of database to index them....
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AbstractMethodError in Java
1. Overview Sometimes, we may encounter AbstractMethodError at runtime in our application. If we don't know this error well, it might take a while to determine the cause of the problem. In this...
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