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
In this quick tutorial, we’re going to look at how to work with boolean values in Thymeleaf.
Before we dive into the details, Thymeleaf basics can be found in this write-up.
2. Evaluating Expressions as Booleans
In Thymeleaf, any value can be evaluated to a boolean. We have a few values interpreted as false:
- null
- the boolean value false
- the number 0
- the character \0
- the strings “false”, “off”and “no”
Any other value is evaluated to true.
3. Using Booleans as a Rendering Conditions
To render an HTML element conditionally, we have two options: the th:if and the th:unless attributes.
Their effect is exactly the opposite – Thymeleaf will render an element with a th:if attribute only if the attribute’s value is true and with th:unless attribute only if its value is false:
<span th:if="${true}">will be rendered</span>
<span th:unless="${true}">won't be rendered</span>
<span th:if="${false}">won't be rendered</span>
<span th:unless="${false}">will be rendered</span>4. Logical and Conditional Operators
In addition, we can use the three classic logic operators in Thymeleaf:
- and
- or
- negation with the keyword not or the “!” symbol
We can use these operators inside variable expressions or combining multiple variable expressions with them:
<span th:if="${isRaining or isCold}">The weather is bad</span>
<span th:if="${isRaining} or ${isCold}">The weather is bad</span>
<span th:if="${isSunny and isWarm}">The weather is good</span>
<span th:if="${isSunny} and ${isWarm}">The weather is good</span>
<span th:if="${not isCold}">It's warm</span>
<span th:if="${!isCold}">It's warm</span>
<span th:if="not ${isCold}">It's warm</span>
<span th:if="!${isCold}">It's warm</span>We can also use conditional operators: the if-then, if-then-else, and the default operators.
The if-then-else operator is the usual ternary, or ?: operator:
It's <span th:text="${isCold} ? 'cold' : 'warm'"></span>Moreover, the if-then operator is the simplified version where we don’t have an else part:
<span th:text="${isRaining or isCold} ? 'The weather is bad'"></span>The default operator returns the first operand if it’s not null and the second otherwise:
<span th:text="'foo' ?: 'bar'"></span> <!-- foo -->
<span th:text="null ?: 'bar'"></span> <!-- bar -->
<span th:text="0 ?: 'bar'"></span> <!-- 0 -->
<span th:text="1 ?: 'bar'"></span> <!-- 1 -->The default operator is also called the Elvis operator because of its strong resemblance to Elvis’ hairstyle.
Note, that the Elvis operator only does a null check, it doesn’t evaluate the first operand as boolean.
5. #bools Utility Object
The #bools is a utility object which is available in expressions by default and has some handy methods:
- #bools.isTrue(obj) returns whether the argument is evaluated to true
- #bools.isFalse(obj) returns whether the argument is evaluated to false
- #bools.xxxIsTrue(collection) converts the elements of the argument to booleans with #bools.isTrue() then collects them to the same type of collection
- #bools.xxxIsFalse(collection) converts the elements of the argument to booleans with #bools.isFalse() then collects them to the same type of collection
- #bools.xxxAnd(collection) returns true if all elements in the argument is evaluated to true
- #bools.xxxOr(collection) returns true if any element in the argument is evaluated to true
In the methods above xxx can be either array, list or set, depending on the method’s argument (and return value in case of xxxIsTrue() and xxxIsFalse()).
6. Conclusion
In this article, we’ve seen how Thymeleaf interprets values as booleans, also how we can render elements conditionally and work with boolean expressions.
