Handling back button in Android Navigation Component

Question

I\'d like to know how properly handle system back button action using Navigation Controller. In my app I have two fragments (for ex. fragment1 and fragment2) and I have an a

Answer 1

If you are using BaseFragment for your app then you can add onBackPressedDispatcher to your base fragment.

//Make a BaseFragment for all your fragments
abstract class BaseFragment : Fragment() {

private lateinit var callback: OnBackPressedCallback

/**
 * SetBackButtonDispatcher in OnCreate
 */

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setBackButtonDispatcher()
}

/**
 * Adding BackButtonDispatcher callback to activity
 */
private fun setBackButtonDispatcher() {
    callback = object : OnBackPressedCallback(true) {
        override fun handleOnBackPressed() {
            onBackPressed()
        }
    }
    requireActivity().onBackPressedDispatcher.addCallback(this, callback)
}

/**
 * Override this method into your fragment to handleBackButton
 */
  open fun onBackPressed() {
  }

}

Override onBackPressed() in your fragment by extending basefragment

//How to use this into your fragment
class MyFragment() : BaseFragment(){

private lateinit var mView: View

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    mView = inflater.inflate(R.layout.fragment_my, container, false)
    return mView.rootView
}

override fun onBackPressed() {
    //Write your code here on back pressed.
}

}