Java has several solid REPL implementations available. Here are the main options and how to use them. jshell (Official) The best choice for most users is jshell, included in JDK 9+. It’s the official interactive shell for Java and comes with every modern Java installation. Start it immediately: jshell Basic usage: jshell> long ts =…
When you install a JDK on Linux, you need to configure environment variables so your shell uses the correct Java binary and build tools can locate the installation. If you have multiple Java versions installed, proper configuration becomes essential. Why Set Java Environment Variables Setting JAVA_HOME and PATH ensures: Tools and applications can locate the…
Scala runs on the JVM and combines object-oriented and functional programming. Here’s how to install Scala on Fedora Linux using several methods. Method 1: Install via Coursier (Recommended) Coursier is the official Scala installer and handles JDK dependencies automatically: # Install Coursier curl -fL https://github.com/coursier/coursier/releases/latest/download/cs-x86_64-pc-linux.gz | gzip -d > cs && chmod +x cs &&…
Spring Shell is a framework for building command-line interfaces (CLIs) in Java applications. It provides structured command definition, argument parsing, tab completion, and history management—all integrated with the Spring ecosystem. Requirements and Setup Spring Shell 3.2+ requires Java 17+ and Spring Boot 3.2+. If you’re still on older versions, Spring Shell 2.x supports Java 8…
Hadoop 2.x reached end-of-life in 2016. This guide covers setup for learning purposes and legacy system maintenance only. For production deployments, use Hadoop 3.x or later, which includes performance improvements, better YARN scheduling, HDFS erasure coding, and improved security. Cloud-managed options like AWS EMR, Google Dataproc, and Azure HDInsight eliminate most operational overhead. This guide…
JNI lets you call native C/C++ functions from Java on Windows. This guide covers the complete workflow with modern tooling. Prerequisites JDK 17 or later (JDK 21 LTS recommended) Microsoft Visual Studio 2022 or Visual Studio Build Tools MSVC C/C++ compiler javac for compilation and header generation Step 1: Write the Java Code Create your…
Hadoop 1.x reached end-of-life in 2014 and is no longer maintained. This post documents a deprecated architecture for historical reference only. For new deployments, use Hadoop 3.x+ with YARN, which offers significant improvements in resource management, multi-tenancy, and reliability. See the Apache Hadoop documentation for current versions. For managed services, consider AWS EMR, Google Dataproc,…