I don t do it to avoid that its type can be null I do it to

Question

I don t do it to avoid that its type can be null I do it to handle the fact those properties are non null but can t be initialized until `onCreate` is called in that case I think `lateinit` is a godsend

alex.tavella · Answer

Exactly I agree with you However static analysis tools such as detekt consider the usage of lateinit a bad practice for property initialization and I m trying to convince my team that it could be used for that purpose

arekolek · Answer

Does the team have some other opinion on that If so what s their alternative

arekolek · Answer

I bet detekt means lateinit is bad in case it can be replaced with ordinary non null property

arekolek · Answer

I think nullable property is a lot worse than lateinit

alex.tavella · Answer

Their alternative is make the property nullable

alex.tavella · Answer

arekolek · Answer

gt Try using constructor injection or delegation to initialize properties I think that s the key

arekolek · Answer

you can do `var dependency SomeType by Delegates notNull ` but it s effectively the same as lateinit

alex.tavella · Answer

Behind the scenes its the same thing though

arekolek · Answer

so if you can t do constructor injection as is the case for activities and fragments and others you re left with lateinit

alex.tavella · Answer

Yup

arekolek · Answer

see also <https github com arturbosch detekt pull 127 issuecomment 310912474>

arekolek · Answer

when introducing that rule they said explicitly they wouldn t want to enforce it by default because of activities for example

alex.tavella · Answer

Do you think its a different scenario when assigning binding from databinding properties They have to be assigned from Fragment onCreateView or Activity onCreate

arekolek · Answer

like with butterknife

arekolek · Answer

I d make such property nullable only if it is optional

arekolek · Answer

if I expect it to always be there I make it lateinit as well

alex.tavella · Answer

Yea that s my approach also

arekolek · Answer

yeah so for the result of `DataBindinUtil` `setContentView` and similar I use lateinit as well no reason to make it nullable

arekolek · Answer

but sometimes it doesn t need to be a class property it can be local

arekolek · Answer

and it s not nullable then obviously so why make it nullable when it s a class property

alex.tavella · Answer

But most of the times you assign the viewmodel to the binding after onCreateView

alex.tavella · Answer

So it makes sense that it is a class property

arekolek · Answer

agreed

alex.tavella · Answer

Well so I ll keep trying to convince them Thanks for the insights

arekolek · Answer

good luck smile

alex.tavella · Answer

Team decided to go with lateinit clap

alex.tavella · Answer

As a matter of fact it was all a misunderstanding

thymecypher · Answer

Yeah definitely use lateinit Kotlin is designed to have the flexibility and syntax of modern managed languages but it tends to follow a lot of the rules of microprocessor development when it comes to how you should approach things Which makes sense why we have Kotlin Native and micro support for it

thymecypher · Answer

I actually aim to never use var when writing Kotlin

thymecypher · Answer

But in this case its ok It was put there for a reason