方法不会覆盖任何内容Play Framework Scala

Question

I am implementing dependency injection in play Framework version 2.3.8 using guice. Below is implementation of getControllerInstance of GlobalSettings trait.

import com.google.inject.{ Guice, AbstractModule }
import play.api.GlobalSettings
import services._

object Global extends GlobalSettings {  
  val injector = Guice.createInjector(new AbstractModule {
    protected def configure() {
      bind(classOf[CategoryService]).to(classOf[CategoryServiceImpl])
    }
  })

  override def getControllerInstance[A](controllerClass: Class[A]): A = {
    injector.getInstance(controllerClass)
  }
}

When I compile the project, it gives Method overrides Nothing error. Below is the complete error description.

[error] /home/rajkumar/scalacb/PlayFrameworkCookbook/Handwritten /PFCChapter3Guice/app/Global.scala:14: method getControllerInstance overrides nothing
[error]   override def getControllerInstance[A](controllerClass: Class[A]): A = {
[error]                ^
[error] one error found
[error] (compile:compileIncremental) Compilation failed

After removing the override in front of getControllerInstance, the compilation is successful. After I ran the project, it throws different error.

Below is the complete error trace.

! @6ol3cn5pi - Internal server error, for (GET) [/categories] ->

play.api.UnexpectedException: Unexpected   exception[ProvisionException:     Unable to provision, see the following   errors:

1) No implementation for services.CategoryService was bound.
while locating services.CategoryService
  for parameter 0 at controllers.CategoryController.<init>   (CategoryController.scala:7)
  while locating com.google.inject.Provider<controllers.CategoryController>
  for parameter 2 at router.Routes.<init>(Routes.scala:35)
  while locating router.Routes
  while locating play.api.inject.RoutesProvider
  while locating play.api.routing.Router 1 error]

Thanks in advance for your kind help.

Answer 1

I think you should first double check that you are actually using Play 2.3.8, you can look in plugins.sbt to find out.

If it turns out that you are actually using Play 2.4, then I'm afraid it looks like the error message is correct in that getControllerInstance does not exist for you as this link shows https://www.playframework.com/documentation/2.4.x/api/java/play/GlobalSettings.html