Is it required to add @Singleton on top of a function using dagger hilt if the module scope is already singleton?

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In the below code, I have a module where I call @InstallIn(SingletonComponent::class). So the scope of this module is the application scope or singleton scope)) If I'll provide something inside the module, do I need to annotate that function with singleton as well?

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dagger-hilt kotlin android
1 Answers

Yes you have to annotate that function with singleton as well.

@InstallIn(SingletonComponent::class) means that you may use singleton in your @Provides functions, without it you can't make your @Provides functions singleton. In hilt @Provides functions have no-scope by default so if you don't annotate your @Provides function with singleton, every time it will return new object.

you can easily test my answer with below code

var count = 0

class TestingClass() {
    init {
        count++
    }

    fun printCount() = println("count: $count")
}

@Module
@InstallIn(SingletonComponent::class)
class TestModule {

    @Provides
    @Singleton // without this count will increase every time you inject TestingClass
    fun provideTestClass(): TestingClass {
        return TestingClass()
    }
}
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