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Java / MapStruct Java Interview questions part 2

How do you add MapStruct to a Maven project?

MapStruct needs two things in Maven: the core dependency for compilation and runtime, and the annotation processor registered on the compiler plugin.

<dependency>
  <groupId>org.mapstruct</groupId>
  <artifactId>mapstruct</artifactId>
  <version>1.6.3</version>
</dependency>

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <configuration>
    <annotationProcessorPaths>
      <path>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct-processor</artifactId>
        <version>1.6.3</version>
      </path>
    </annotationProcessorPaths>
  </configuration>
</plugin>

Without registering the processor, javac never invokes MapStruct and no implementation class is produced, so calling Mappers.getMapper(...) at runtime would fail with a "no implementation found" error. Keeping the mapstruct and mapstruct-processor versions aligned avoids subtle mismatches between the annotations you compile against and the generator that reads them.

What happens if the mapstruct-processor is not registered on the compiler plugin?
Which Maven dependency provides the annotations used at compile and runtime?

More Related questions...

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