the concept of them?

yeah

i imagine it’d be pretty hard to build, say, Spring Boot without them

if you’re building a library, you don’t always know what the client is gong to have aavilable at runtime

on a frameworklevel maybe, but for applications it should rarely be necessary

but that doesn't answer your question 😄

another potential use is for testability, for various reasons you may not want to actual include a dependency at test time

i would always go for injecting a mock or a noop implementation in that case

you mock them instead. Making production code more complicated for tests is not a good practice

this

one day you mess up your production spring configuration and nothing breaks

because all the calls are conditional

oh definitely, can certainly be abused

i think i would go down that NOOP implementation route also for production

hard dependencies but they can decide to do nothing

the complexity and information is hidden from the caller

if that injected dependency chooses to do nothing with my invocation is not for me to decide

but i'm sure there are cases where this is not possible

sorry for hijacking your question 😆

haha no prob

i generally agree with you that it isn’t generally as useful for app code, should mostly be used in libraries/shared code

@madorb yes. a quick test with spring boot 2 + kotlin confirmed it.

anyone know why

mvn spring-boot:run

won't start my application? I've got the spring boot maven plugin in my build settings.

ah I think it's due to my sources being in

src/main/kotlin

where do I specify I want to use

src/main/kotlin

and not

src/main/java

?

Thank you @sdeleuze I think I generated this project with start.spring.io so maybe that needs to be updated?

hmm. still getting

Execution package-springboot-executable of goal org.springframework.boot:spring-boot-maven-plugin:1.5.6.RELEASE:repackage failed: Unable to find main class

If I make my build config

<build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.company.document.documentrequirementsservice.DocumentRequirementsServiceApplicationKt</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

Project generated with start.spring.io have that conf in the parent POM