What is Spring Data JPA?
Spring Data JPA is a module of Spring Data that simplifies the implementation of repositories. It provides an automatic way to create repository implementations based on Java interfaces, eliminating the need to manually write the repository implementation. To make this work, you need to create an interface using the @Repository annotation and extend JpaRepository. The…
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How to avoid NullPointerException in Java using Optional?
Optional was introduced in Java 8 as a way to handle potentially null values more safely and expressively. It helps to avoid NullPointerException and makes the code more readable. Hands on Creating an Optional Optional can be created in several ways: Printing the results will show the following output. Checking for Value Presence Optional provides…
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How to create an Interceptor in Angular and Why?
In Angular, an Interceptor is an feature that allows intercepting HTTP requests . This enables you to add logic such as: Hands on We can create an Interceptor with the following command. Now, let’s create an Interceptor to add JWT tokens. This is a real example of an Interceptor. We have a service that retrieves…
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What is algorithm complexity?
Algorithm complexity is a fundamental concept in computer science, used to measure the efficiency of an algorithm in terms of execution time and memory usage. By analyzing complexity, we can predict how an algorithm behaves as the input size increases, allowing us to choose more appropriate solutions for different problems. How do we measure it?…
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How do @PostConstruct and @PreDestroy annotation work in java?
Methods annotated with @PostConstruct and @PreDestroy are commonly used in the lifecycle of beans managed by the container, such as in frameworks like Spring or Quarkus. An example of their use is opening and closing database connections. If you want to know more about Bean management in Spring, don’t hesitate to read this post. @PostConstruct…
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How do functional interfaces work in Java?
Functional Interfaces are a fundamental concept in functional programming introduced in Java 8. They are interfaces that have exactly one abstract method, allowing the use of lambda expressions and method references to make the code more concise and readable. They can be used in Streams, for example, and promote code reuse. We can find several…
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How do @Input and @Output work in Angular?
In Angular, @Input and @Output are essential decorators that facilitate communication between components. They allow data to be passed from a parent to a child component (@Input) and events to be emitted from a child to a parent component (@Output). @Input It allows the child component to receive values from the parent component. The parent…
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What is Shallow Copy and Deep Copy in Java?
When developing software, there may be situations where it is necessary to create copies of objects to prevent unwanted behaviors, whether to avoid different parts of the system modifying the same object or for any other reason that prevents undesired behavior. Java provides the Cloneable interface, which allows object copying. There are two types of…
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What is Factory Method?
The Factory Method is a creational design pattern that provides an interface for creating objects in a superclass but allows subclasses to alter the type of objects that will be created. In addition to the use of polymorphism, it is possible to create either ProductA or ProductB, depending on which factory is being used. The…
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Why use Abstract Classes in Java?
Abstract classes in Java are templates that cannot be instantiated directly and may include abstract methods (without implementation) and concrete methods (with implementation). They are used to define common behaviors that subclasses must implement while sharing reusable code. Abstract methods act as placeholders, enforcing a contract that subclasses must fulfill. Let’s look at an example.…
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