CODEWITHSUNDEEP
androiddependency-injectionkotlindagger-2
lannyf
lannyf

Reputation: 11025

dagger 2, what is difference between @set:Inject and @Inject

In a android, kotlin project, seeing this @set:Inject but could not find a good explanation. Anyone knows?

object Controller {

    @set:Inject
    lateinit var someData: SomeData

Upvotes: 7

Views: 3154

Answers (1)

Sergii Zhevzhyk
Sergii Zhevzhyk

Reputation: 4202

The @Inject annotation can be used for method, constructor, or field:

@Target(value={METHOD,CONSTRUCTOR,FIELD})

It is important to remember that Java code will be generated from this Kotlin code and for one statement in Kotlin you can have multiple Java elements and that is why @set:Inject explicitly specifies that the @Inject annotation should be applied to the setter that will be generated in Java.

What happens if there is no use-site target defined? Official documentation provides a good explanation:

If you don't specify a use-site target, the target is chosen according to the @Target annotation of the annotation being used. If there are multiple applicable targets, the first applicable target from the following list is used:

  • param (constructor parameter);
  • property (annotations with this target are not visible to Java);
  • field;

Upvotes: 12

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