Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.
Get started with understanding multi-threaded applications with our Java Concurrency guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
Refactor Java code safely — and automatically — with OpenRewrite.
Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.
Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.
Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.
Distributed systems often come with complex challenges such as service-to-service communication, state management, asynchronous messaging, security, and more.
Dapr (Distributed Application Runtime) provides a set of APIs and building blocks to address these challenges, abstracting away infrastructure so we can focus on business logic.
In this tutorial, we'll focus on Dapr's pub/sub API for message brokering. Using its Spring Boot integration, we'll simplify the creation of a loosely coupled, portable, and easily testable pub/sub messaging system:
1. Introduction
Java is a widely used programming language that offers various mechanisms for managing dependencies and organizing code.
In the same context, modulepath and classpath are two fundamental concepts for managing dependencies in Java. Moreover, understanding the difference between these two is crucial for efficient Java development.
In this tutorial, we’ll explore the distinctions between the modulepath and classpath and their significance in Java applications.
2. Dependencies in Java
Dependencies refer to external libraries, modules, or packages required for a Java program to compile and run successfully. These dependencies often provide additional functionalities or resources unavailable in the core libraries. Managing dependencies effectively ensures that the required resources are available at runtime.
3. Classpath in Java
Classpath is an environment variable that tells the Java Virtual Machine (JVM) where to find classes and resources during runtime.
It consists of a collection of directories, JAR, and ZIP files that contain compiled Java bytecode (.class files) and associated resources such as configuration files, property files, and other assets.
When a Java program is executed, the JVM uses the classpath to locate the required classes and resources. Additionally, it allows the JVM to load classes from different locations, including the Java standard library, external libraries, and project-specific code.
Here’s an example of using the classpath:
javac -cp "lib/mylibrary.jar" MyProgram.java
java -cp "lib/mylibrary.jar:." MyProgramIn the above code, the -cp option specifies the classpath. We include the lib/mylibrary.jar file in the classpath using the -cp option and the current directory (.) where the program’s class files reside.
4. Modulepath in Java
It is a collection of directories, JAR files, and modules that contain compiled module files (.mod files) and their associated dependencies.
In addition, when a modular Java program is executed, the JVM uses the modulepath to resolve modules and their dependencies.
Here’s an example of using the modulepath:
javac --module-source-path project -d mods --module moduleA --module moduleB
java --module-path mods --module moduleB/com.example.ModuleB
In the above code, the –module-source-path option specifies the root directory of the modules, and the -d option indicates the output directory for compiled module files (mods directory in this case).
The –module-path option specifies the modulepath, which includes the mods directory containing the compiled module files. We then specify the main module (moduleB) and the main class (com.example.ModuleB) to run.
5. Differences Between Modulepath and Classpath
To effectively manage dependencies, achieve modularity, and optimize performance in all Java applications, it’s essential to understand the differences between the modulepath and classpath clearly.
Hence, the following table summarizes the key differences between them:
| Classpath | Modulepath |
|---|---|
| Handles dependencies at a granular level using class files and JAR files | Enforces explicit dependency declarations at the module level |
| Doesn’t enforce explicit dependency declarations, leading to potential issues | Ensures a clear understanding of required resources, avoiding conflicts |
| All classes and resources are globally accessible by default | Promotes encapsulation and controlled visibility |
| Unrestricted accessibility can lead to naming conflicts or unintended dependencies | Prevents unwanted dependencies. Since the only exported packages are accessible by other modules |
| Less efficient since it requires searching through directories and JAR files | More efficient by building a dependency graph and loading only required modules, improving performance |
| The search process can be time-consuming, especially for large classpaths | Reduces search overhead, enhancing runtime performance |
6. Conclusion
In this article, we discussed the distinction between the modulepath and classpath, crucial for effective dependency management, modularity, and performance optimization in Java applications.
