What is the use of @component in Java?

@Component is an annotation that allows Spring to automatically detect our custom beans. In other words, without having to write any explicit code, Spring will: Scan our application for classes annotated with @Component. Instantiate them and inject any specified dependencies into them.

What is @component in Java?

A component is the fundamental user interface object in Java. Everything you see on the display in a Java application is a component. This includes things like windows, panels, buttons, checkboxes, scrollbars, lists, menus, and text fields. To be used, a component usually must be placed in a container.

What is @component used for?

Spring Component annotation is used to denote a class as Component. It means that Spring framework will autodetect these classes for dependency injection when annotation-based configuration and classpath scanning is used.

Does @component create a bean?

We cannot create a bean of a class using @Component, if the class is outside spring container whereas we can create a bean of a class using @Bean even if the class is present outside the spring container.

What is the difference between @component and @ComponentScan?

The main difference between these annotations is that @ComponentScan scans for Spring components while @EnableAutoConfiguration is used for auto-configuring beans present in the classpath in Spring Boot applications.

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Is @component a singleton?

Yes, that is correct, @Component is a Spring bean and a Singleton. About singletons – spring beans are all in singleton scope by default. The only thing you have to have in mind is that you should not store state in field variables (they should only hold dependencies).

What are the three components of JVM?

As shown in the above architecture diagram, the JVM is divided into three main subsystems:

  • ClassLoader Subsystem.
  • Runtime Data Area.
  • Execution Engine.

What is difference between @component and @service?

@Component serves as a generic stereotype for any Spring-managed component; whereas, @Repository, @Service, and @Controller serve as specializations of @Component for more specific use cases (e.g., in the persistence, service, and presentation layers, respectively).

What is an example of component?

The definition of component means one part of a whole thing. An example of a component is the CD player in a stereo system. An example of a component is an ingredient in a recipe. … One element of a larger system.

What is the use of component diagram?

The purpose of a component diagram is to show the relationship between different components in a system. For the purpose of UML 2.0, the term “component” refers to a module of classes that represent independent systems or subsystems with the ability to interface with the rest of the system.

What is difference between @bean and Autowired?

Annotating @Bean only registers the service as a bean(kind of an Object) in spring application context. In simple words, it is just registration and nothing else. Annotating a variable with @Autowired injects a BookingService bean(i.e Object) from Spring Application Context.

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When should I use @bean?

When should we use it? First, @Bean is an annotation that used for annotating the function (not a class) that will return an object of a class that will be registered as a bean object by Spring. You could use it in case you are using a third-party library when you don’t have access to the source code of the library.

When should we use @bean?

@Bean works in conjunction with a configuration class (with @Configuration) and thus in the annotation based configuration. It also is used on the methods inside of such a configuration class. Telling Spring to add whatever the method returns to the Spring Context. It’s done explicitly.

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