Unresolved reference error when using viewLifecycleOwner

Issue

I am having an error using Observer and viewLifecycleOwner in my android project. It throws a "Unresolved reference: viewLifecycleOwner" error and I have no clue why. I verified I had the imports

import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider

And the dependency:

implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'

I have tried to Invalidate Caches / Restart... solution found in GitHub. But the error persists. Thanks to anyone who can help me.

class MainActivity : AppCompatActivity() {
    private lateinit var viewModel: DrinkViewModel

    // Contains all the views
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        viewModel = ViewModelProvider(this).get(MyViewModel::class.java)

        // Use Data Binding to get reference to the views
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main)

        binding.drinkButton.setOnClickListener {
            onDrinkClicked()
        }

        viewModel.revenue.observe(viewLifecycleOwner, Observer { newRevenue ->
            binding.revenueText.text = newRevenue.toString()
        })

        viewModel.drinksSold.observe(viewLifecycleOwner, Observer { newAmount ->
            binding.amountSoldText.text = newAmount.toString()
        })
        binding.drinkButton.setImageResource(viewModel.currentDrink.value!!.imageId)
    }
}

Solution

getViewLifecycleOwner() is method to represent fragment's lifeCycle. You can't call it from activiy scope. You can just use this or if you are familiar with coroutines, you can use lifeCycleScope .

Answered By - Berkay Kireçci