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eBook – Mockito – NPI EA (tag = Mockito)
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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.

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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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.

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eBook – Reactive – NPI EA (cat=Reactive)
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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:

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eBook – Java Streams – NPI EA (cat=Java Streams)
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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:

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eBook – Jackson – NPI EA (cat=Jackson)
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Do JSON right with Jackson

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eBook – HTTP Client – NPI EA (cat=Http Client-Side)
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eBook – Maven – NPI EA (cat = Maven)
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eBook – Persistence – NPI EA (cat=Persistence)
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eBook – RwS – NPI EA (cat=Spring MVC)
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Course – LS – NPI EA (cat=Jackson)
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Course – RWSB – NPI EA (cat=REST)
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Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:

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Course – LSS – NPI EA (cat=Spring Security)
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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:

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Course – LSD – NPI EA (tag=Spring Data JPA)
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Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.

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Partner – Moderne – NPI EA (cat=Spring Boot)
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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.

Course – LJB – NPI EA (cat = Core Java)
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Partner – LambdaTest – NPI EA (cat= Testing)
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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:

>> Flexible Pub/Sub Messaging With Spring Boot and Dapr

1. Overview

In this article, we’ll discuss the Abstract Factory design pattern.

The book Design Patterns: Elements of Reusable Object-Oriented Software states that an Abstract Factory “provides an interface for creating families of related or dependent objects without specifying their concrete classes”. In other words, this model allows us to create objects that follow a general pattern.

An example of the Abstract Factory design pattern in the JDK is the newInstance() of javax.xml.parsers.DocumentBuilderFactory class.

2. Abstract Factory Design Pattern Example

In this example, we’ll delve into the Abstract Factory pattern using a Java example that involves prehistoric animals.

To illustrate the Abstract Factory pattern, we’ll consider a scenario involving prehistoric animals. These animals can be categorized by their era (Mesozoic or Cenozoic) and their type (land or sky animals). We’ll create a system that allows us to create and manage these animals using the Abstract Factory pattern.
After that, we’ll manage access to them using an abstract factory AnimalAbstractFactory:
Class Diagram
Components of the Abstract Factory Pattern
We start by defining two enums, AnimalEra and AnimalType, to represent the eras (Mesozoic and Cenozoic) and animal types (land and sky).
public enum AnimalEra {
    MESOZOIC,
    CENOZOIC
}

public enum AnimalType {
    LAND,
    SKY
}

Abstract Product Class: Animal

Next, we create an abstract class Animal to define the common attributes of our animals: their era, type, and name. It also includes an abstract create() method, which will be implemented by concrete subclasses.

public abstract class Animal {
    AnimalType type;
    AnimalEra era;
    String name;

    Animal(AnimalType type, AnimalEra era, String name) {
        this.type = type;
        this.era = era;
        this.name = name;
    }

    abstract void create();
}
Concrete Product Classes: LandAnimal and SkyAnimal
We create two concrete subclasses of Animal: LandAnimal and SkyAnimal. These classes provide specific implementations for creating land and sky animals, respectively:
public class LandAnimal extends Animal {
    // Implementation for creating land animals
}

public class SkyAnimal extends Animal {
    // Implementation for creating sky animals
}

We’ll skip the full code here, but it can be found in the source project.

EraAnimalFactory factory interface
We define an interface, EraAnimalFactory, which declares methods for creating land and sky animals per era. Concrete factory classes will implement this interface to create animals of specific eras.
public interface EraAnimalFactory {

    LandAnimal makeLandAnimal();
    SkyAnimal makeSkyAnimal();
}
Concrete Factory Classes: CenozoicAnimalFactory and MesozoicAnimalFactory
We create two concrete factory classes, CenozoicAnimalFactory and MesozoicAnimalFactory, which implement the EraAnimalFactory interface. Each factory is responsible for creating animals from a particular era.
public class CenozoicAnimalFactory implements EraAnimalFactory {
    // Implementation for creating Cenozoic animals
}

public class MesozoicAnimalFactory implements EraAnimalFactory {
    // Implementation for creating Mesozoic animals
}
Abstract factory: AnimalAbstractFactory
AnimalAbstractFactory class is responsible to create animals based on the era and type provided.
public class AnimalAbstractFactory {
    Animal animal;

    Animal createAnimal(AnimalType type) {
        AnimalEra era = getFromConfiguration();

        switch (era) {
            case MESOZOIC:
                animal = new MesozoicAnimalFactory().createAnimal(type);
                break;
            case CENOZOIC:
                animal = new CenozoicAnimalFactory().createAnimal(type);
                break;
        }

        return animal;
    }

    AnimalEra getFromConfiguration() {
        return AnimalEra.MESOZOIC; // Default configuration
    }
}
Running the Example
Finally, we have a client class that demonstrates how to use the AnimalAbstractFactory to create prehistoric animals based on their type. The client doesn’t know anything about the inner factories, he just asks for a land animal. This pattern provides an extra level of abstraction.
public class AbstractFactoryRunner {

    public static void main(String[] args) {
        new AnimalAbstractFactory().createAnimal(AnimalType.LAND);
    }
}

3. When to Use Abstract Factory Pattern:

  • The client is independent of how we create and compose the objects in the system
  • The system consists of multiple families of objects, and these families are designed to be used together
  • We need a run-time value to construct a particular dependency

While the pattern is great when creating predefined objects, adding the new ones might be challenging. To support the new type of objects will require changing the AbstractFactory class and all of its subclasses.

4. Summary

In this article, we learned about the Abstract Factory design pattern.

The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
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Once the early-adopter seats are all used, the price will go up and stay at $33/year.

eBook – HTTP Client – NPI EA (cat=HTTP Client-Side)
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The Apache HTTP Client is a very robust library, suitable for both simple and advanced use cases when testing HTTP endpoints. Check out our guide covering basic request and response handling, as well as security, cookies, timeouts, and more:

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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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:

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eBook – Java Streams – NPI EA (cat=Java Streams)
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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:

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eBook – Persistence – NPI EA (cat=Persistence)
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Course – LS – NPI EA (cat=REST)

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Partner – Moderne – NPI EA (tag=Refactoring)
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Modern Java teams move fast — but codebases don’t always keep up. Frameworks change, dependencies drift, and tech debt builds until it starts to drag on delivery. OpenRewrite was built to fix that: an open-source refactoring engine that automates repetitive code changes while keeping developer intent intact.

The monthly training series, led by the creators and maintainers of OpenRewrite at Moderne, walks through real-world migrations and modernization patterns. Whether you’re new to recipes or ready to write your own, you’ll learn practical ways to refactor safely and at scale.

If you’ve ever wished refactoring felt as natural — and as fast — as writing code, this is a good place to start.

Course – LS – NPI (cat=Java)
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eBook Jackson – NPI EA – 3 (cat = Jackson)