FindNavController - None of the following candidates is applicable because of receiver type mismatch:

Issue

I've been doing this Android Studio course and I've stumbled upon a problem with this particular method. For whatever reason, I can use it in every fragment except one, in which apparently can't be imported.

Here is the fragment: (StartFragment)

package com.example.cupcake

import android.app.Fragment
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.navigation.fragment.findNavController
import com.example.cupcake.databinding.FragmentStartBinding

/**
 * This is the first screen of the Cupcake app. The user can choose how many cupcakes to order.
 */
class StartFragment : Fragment() {

    // Binding object instance corresponding to the fragment_start.xml layout
    // This property is non-null between the onCreateView() and onDestroyView() lifecycle callbacks,
    // when the view hierarchy is attached to the fragment.
    private var binding: FragmentStartBinding? = null

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val fragmentBinding = FragmentStartBinding.inflate(inflater, container, false)
        binding = fragmentBinding
        return fragmentBinding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        binding?.apply {
            // Set up the button click listeners
            orderOneCupcake.setOnClickListener { orderCupcake(1) }
            orderSixCupcakes.setOnClickListener { orderCupcake(6) }
            orderTwelveCupcakes.setOnClickListener { orderCupcake(12) }
        }
    }

    /**
     * Start an order with the desired quantity of cupcakes and navigate to the next screen.
     */
    fun orderCupcake(quantity: Int) {
        findNavController().navigate(R.id.action_startFragment_to_flavorFragment) //here is the error
    }

    /**
     * This fragment lifecycle method is called when the view hierarchy associated with the fragment
     * is being removed. As a result, clear out the binding object.
     */
    override fun onDestroyView() {
        super.onDestroyView()
        binding = null
    }
}

The whole code is in the code link, thanks

Solution

Your fragment extends android.app.Fragment - that's the deprecated, should never be used framework fragment. You need to replace your import android.app.Fragment with import androidx.fragment.app.Fragment to actually extend the AndroidX Fragment you need to use with Navigation.

Answered By - ianhanniballake