Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:
Once the early-adopter seats are all used, the price will go up and stay at $33/year.
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.
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.
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.
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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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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:
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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:
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:
Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:
Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:
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:
1. Overview
In this tutorial, we’ll discuss the different join() methods in the Thread class. We’ll go into the details of these methods and some example codes.
Like the wait() and notify() methods, join() is another mechanism of inter-thread synchronization.
You can have a quick look at this tutorial to read more about wait() and notify().
2. The Thread.join() Method
The join method is defined in the Thread class:
public final void join() throws InterruptedException
Waits for this thread to die.
When we invoke the join() method on a thread, the calling thread goes into a waiting state. It remains in a waiting state until the referenced thread terminates.
We can see this behaviour in the following code:
class SampleThread extends Thread {
public int processingCount = 0;
SampleThread(int processingCount) {
this.processingCount = processingCount;
LOGGER.info("Thread Created");
}
@Override
public void run() {
LOGGER.info("Thread " + this.getName() + " started");
while (processingCount > 0) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
LOGGER.info("Thread " + this.getName() + " interrupted");
}
processingCount--;
LOGGER.info("Inside Thread " + this.getName() + ", processingCount = " + processingCount);
}
LOGGER.info("Thread " + this.getName() + " exiting");
}
}
@Test
public void givenStartedThread_whenJoinCalled_waitsTillCompletion()
throws InterruptedException {
Thread t2 = new SampleThread(1);
t2.start();
LOGGER.info("Invoking join");
t2.join();
LOGGER.info("Returned from join");
assertFalse(t2.isAlive());
}
We should expect results similar to the following when executing the code:
[main] INFO: Thread Thread-1 Created
[main] INFO: Invoking join
[Thread-1] INFO: Thread Thread-1 started
[Thread-1] INFO: Inside Thread Thread-1, processingCount = 0
[Thread-1] INFO: Thread Thread-1 exiting
[main] INFO: Returned from joinThe join() method may also return if the referenced thread is interrupted. In this case, the method throws an InterruptedException.
Finally, if the referenced thread was already terminated or hasn’t been started, the call to join() method returns immediately.
Thread t1 = new SampleThread(0);
t1.join(); //returns immediately3. Thread.join() Methods with Timeout
The join() method will keep waiting if the referenced thread is blocked or takes too long to process. This can become an issue as the calling thread will become non-responsive. To handle these situations, we use overloaded versions of the join() method that allow us to specify a timeout period.
There are two timed versions that overload the join() method:
“public final void join(long millis) throws InterruptedException
Waits at most millis milliseconds for this thread to die. A timeout of 0 means to wait forever.”“public final void join(long millis,intnanos) throws InterruptedException
Waits at most millis milliseconds plus nanos nanoseconds for this thread to die.”
We can use the timed join() as below:
@Test
public void givenStartedThread_whenTimedJoinCalled_waitsUntilTimedout()
throws InterruptedException {
Thread t3 = new SampleThread(10);
t3.start();
t3.join(1000);
assertTrue(t3.isAlive());
}
In this case, the calling thread waits for roughly 1 second for the thread t3 to finish. If the thread t3 does not finish in this time period, the join() method returns control to the calling method.
Timed join() is dependent on the OS for timing. So, we cannot assume that join() will wait exactly as long as specified.
4. Thread.join() Methods and Synchronization
In addition to waiting until termination, calling the join() method has a synchronization effect. join() creates a happens-before relationship:
“All actions in a thread happen-before any other thread successfully returns from a join() on that thread.”
This means that when a thread t1 calls t2.join(), all changes done by t2 are visible in t1 on return. However, if we do not invoke join() or use other synchronization mechanisms, we do not have any guarantee that changes in the other thread will be visible to the current thread even if the other thread has been completed.
Hence, even though the join() method call to a thread in the terminated state returns immediately, we still need to call it in some situations.
We can see an example of improperly synchronized code below:
SampleThread t4 = new SampleThread(10);
t4.start();
// not guaranteed to stop even if t4 finishes.
do {
} while (t4.processingCount > 0);To properly synchronize the above code, we can add timed t4.join() inside the loop or use another synchronization mechanism.
5. Conclusion
join() method is quite useful for inter-thread synchronization. In this article, we discussed the join() methods and their behaviour. We also reviewed the code using the join() method.
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.
