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Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Baeldung)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Microsoft – NPI EA (cat= Spring Boot)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, you can get started over on the documentation page.

And, you can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat=Spring)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

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Partner – Orkes – NPI EA (tag=Microservices)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

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eBook – Guide Spring Cloud – NPI EA (cat=Spring Cloud)
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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.

Get started with mocking and improve your application tests using our Mockito guide:

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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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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Get the most out of the Apache HTTP Client

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Building a REST API with Spring?

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Course – LS – NPI EA (cat=Jackson)
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Get started with Spring and Spring Boot, through the Learn Spring course:

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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 – All Access – NPI EA (cat= Spring)
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All Access is finally out, with all of my Spring courses. Learn JUnit is out as well, and Learn Maven is coming fast. And, of course, quite a bit more affordable. Finally.

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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 – LambdaTest – NPI EA (cat=Testing)
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End-to-end testing is a very useful method to make sure that your application works as intended. This highlights issues in the overall functionality of the software, that the unit and integration test stages may miss.

Playwright is an easy-to-use, but powerful tool that automates end-to-end testing, and supports all modern browsers and platforms.

When coupled with LambdaTest (an AI-powered cloud-based test execution platform) it can be further scaled to run the Playwright scripts in parallel across 3000+ browser and device combinations:

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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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eBook – Java Streams – NPI (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:

>> Join Pro and download the eBook

1. Overview

As Java developers, we often write code that iterates over a set of elements and performs an operation on each one. The Java 8 streams library and its forEach method allow us to write that code in a clean, declarative manner.

While this is similar to loops, we are missing the equivalent of the break statement to abort iteration. A stream can be very long, or potentially infinite, and if we have no reason to continue processing it, we would want to break from it, rather than wait for its last element.

In this tutorial, we’re going to look at some mechanisms that allow us to simulate a break statement on a Stream.forEach operation.

2. Java 9’s Stream.takeWhile()

Let’s suppose we have a stream of String items and we want to process its elements as long as their lengths are odd.

Let’s try the Java 9 Stream.takeWhile method:

Stream.of("cat", "dog", "elephant", "fox", "rabbit", "duck")
  .takeWhile(n -> n.length() % 2 != 0)
  .forEach(System.out::println);

If we run this, we get the output:

cat
dog

Let’s compare this with the equivalent code in plain Java using a for loop and a break statement, to help us see how it works:

List<String> list = asList("cat", "dog", "elephant", "fox", "rabbit", "duck");
for (int i = 0; i < list.size(); i++) {
    String item = list.get(i);
    if (item.length() % 2 == 0) {
        break;
    }
    System.out.println(item);
}

As we can see, the takeWhile method allows us to achieve exactly what we need.

But what if we haven’t adopted Java 9 yet? How can we achieve a similar thing using Java 8?

3. A Custom Spliterator

Let’s create a custom Spliterator that will work as a decorator for a Stream.spliteratorWe can make this Spliterator perform the break for us.

First, we’ll get the Spliterator from our stream, then we’ll decorate it with our CustomSpliterator and provide the Predicate to control the break operation. Finally, we’ll create a new stream from the CustomSpliterator:

public static <T> Stream<T> takeWhile(Stream<T> stream, Predicate<T> predicate) {
    CustomSpliterator<T> customSpliterator = new CustomSpliterator<>(stream.spliterator(), predicate);
    return StreamSupport.stream(customSpliterator, false);
}

Let’s look at how to create the CustomSpliterator:

public class CustomSpliterator<T> extends Spliterators.AbstractSpliterator<T> {

    private Spliterator<T> splitr;
    private Predicate<T> predicate;
    private boolean isMatched = true;

    public CustomSpliterator(Spliterator<T> splitr, Predicate<T> predicate) {
        super(splitr.estimateSize(), 0);
        this.splitr = splitr;
        this.predicate = predicate;
    }

    @Override
    public synchronized boolean tryAdvance(Consumer<? super T> consumer) {
        boolean hadNext = splitr.tryAdvance(elem -> {
            if (predicate.test(elem) && isMatched) {
                consumer.accept(elem);
            } else {
                isMatched = false;
            }
        });
        return hadNext && isMatched;
    }
}

So, let’s take a look at the tryAdvance method. We can see here that the custom Spliterator processes the elements of the decorated Spliterator. The processing is done as long as our predicate is matched and the initial stream still has elements. When either of the conditions becomes false, our Spliterator “breaks” and the streaming operation ends.

Let’s test our new helper method:

@Test
public void whenCustomTakeWhileIsCalled_ThenCorrectItemsAreReturned() {
    Stream<String> initialStream = 
      Stream.of("cat", "dog", "elephant", "fox", "rabbit", "duck");

    List<String> result = 
      CustomTakeWhile.takeWhile(initialStream, x -> x.length() % 2 != 0)
        .collect(Collectors.toList());

    assertEquals(asList("cat", "dog"), result);
}

As we can see, the stream stopped after the condition was met. For testing purposes, we’ve collected the results into a list, but we could also have used a forEach call or any of the other functions of Stream.

4. A Custom forEach

While providing a Stream with the break mechanism embedded can be useful, it may be simpler to focus on just the forEach operation.

Let’s use the Stream.spliterator directly without a decorator:

public class CustomForEach {

    public static class Breaker {
        private boolean shouldBreak = false;

        public void stop() {
            shouldBreak = true;
        }

        boolean get() {
            return shouldBreak;
        }
    }

    public static <T> void forEach(Stream<T> stream, BiConsumer<T, Breaker> consumer) {
        Spliterator<T> spliterator = stream.spliterator();
        boolean hadNext = true;
        Breaker breaker = new Breaker();

        while (hadNext && !breaker.get()) {
            hadNext = spliterator.tryAdvance(elem -> {
                consumer.accept(elem, breaker);
            });
        }
    }
}

As we can see, the new custom forEach method calls a BiConsumer providing our code with both the next element and a breaker object it can use to stop the stream.

Let’s try this out in a unit test:

@Test
public void whenCustomForEachIsCalled_ThenCorrectItemsAreReturned() {
    Stream<String> initialStream = Stream.of("cat", "dog", "elephant", "fox", "rabbit", "duck");
    List<String> result = new ArrayList<>();

    CustomForEach.forEach(initialStream, (elem, breaker) -> {
        if (elem.length() % 2 == 0) {
            breaker.stop();
        } else {
            result.add(elem);
        }
    });

    assertEquals(asList("cat", "dog"), result);
}

5. Conclusion

In this article, we looked at ways to provide the equivalent of calling break on a stream. We saw how Java 9’s takeWhile solves most of the problem for us and how to provide a version of that for Java 8.

Finally, we looked at a utility method which can provide us with the equivalent of a break operation while iterating on a Stream.

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.
Baeldung Pro – NPI EA (cat = Baeldung)
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Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:

>> Explore a clean Baeldung

Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Spring Boot)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat = Spring)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

Partner – Orkes – NPI EA (tag = Microservices)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

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:

>> Download the eBook

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:

>> Join Pro and download the eBook

eBook – Persistence – NPI EA (cat=Persistence)
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Working on getting your persistence layer right with Spring?

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Course – LS – NPI EA (cat=REST)

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Get started with Spring Boot and with core Spring, through the Learn Spring course:

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Course – Spring Sale 2025 – NPI EA (cat= Baeldung)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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Course – Spring Sale 2025 – NPI (All)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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eBook – Java Streams – NPI (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:

>> Join Pro and download the eBook

eBook Jackson – NPI EA – 3 (cat = Jackson)