Hello friends, I’m experiencing NullPointerExceptions on my fragments when I migrated it to ViewBind...

# android

[Law Gimenez]

Hello friends, I’m experiencing NullPointerExceptions on my fragments when I migrated it to ViewBinding. I am following exactly based on the documentation https://developer.android.com/topic/libraries/view-binding#kts but it will throw NullPointerException on the private val binding get() = _binding!! line. Thanks in advance for the help!

[wbertan]

Can you make sure you are not calling it before the onCreateView and after the onDestroyView?

// This property is only valid between onCreateView and

// onDestroyView.

private val binding get() = _binding!!

[wbertan]

Quick and dirty one to check:

private var _binding: ResultProfileBinding? = null
    // This property is only valid between onCreateView and
    // onDestroyView.
    private val binding: ResultProfileBinding get() {
        println("test binding get")
        return _binding!!
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        println("test onCreateView")
        _binding = ResultProfileBinding.inflate(inflater, container, false)
        val view = binding.root
        return view
    }

    override fun onDestroyView() {
        println("test onDestroyView")
        super.onDestroyView()
        _binding = null
    }

Look in the Logcat to see if the test binding get calls either before the test onCreateView or after the test onDestroyView.

[Law Gimenez]

Thanks for the code snippet @wbertan and yes I am not calling it before onCreateView and after onDestroyView. I did follow everything on the Android documentation link. I will try your implementation.

[wbertan]

Asking as we are having some crashes related to this too. We had a leak somewhere where it was calling it after the onDestroyView in some cases only due to the leak 😞

[Law Gimenez]

The issue is when I try to click rapidly on each Fragment. The Fragment is hosted on the BottomNavigationView . It seems ViewBinding can’t catch up on the rendering.

[Law Gimenez]

Can you @ me on your progress @wbertan? If you made some improvements or fixes

[wbertan]

We are also using the same implementation as the docs 😞
Could be something like our case, some listener, etc. which outlives the Fragment View and it calls after the onDestroyView.
In some places after migrating to View Binding we also had to explicitly remove listeners on the onDestroyView.

[FunkyMuse]

https://github.com/FunkyMuse/KAHelpers/blob/master/viewbinding/src/main/java/com/crazylegend/viewbinding/FragmentViewBindingDelegate.kt

[Joost Klitsie]

you have to reinitialize always when you create a view, so in fragments any time onCreateView is called the view binding has to be initialized. Fragments views can be recreated

[Joost Klitsie]

you can use a delegation method to do this automagically

[Law Gimenez]

Thanks let me check that out. Do you have an example as my guide?