Setting setOnClickListener using bindings android kotlin

Question

I have been doing a tutorial that is a bit out of date and uses synthetics rather than bindings. I am trying to use bindins. I am trying to set up a listener in a fragment (AddEditFragment.kt). It's using a callback to MainActivity.onSaveClicked.

In AddEditFragment I use an import for the binding

import com.funkytwig.tasktimer.databinding.FragmentAddEditBinding

I have a lateinit on the first line of the class defenition

class AddEditFragment : Fragment() {
    private lateinit var binding: FragmentAddEditBinding

I am initializing the bunding in onActivityCreated and setting up the listner. I can use findViewById to get the ID

override fun onActivityCreated(savedInstanceState: Bundle?) {
    super.onActivityCreated(savedInstanceState)
    val addEditSave = view?.findViewById(R.id.addEditSave) as Button
    addEditSave.setOnClickListener { listener?.onSaveClicked() }
}

And this works fine but if I try to use the binding

override fun onActivityCreated(savedInstanceState: Bundle?) {
    super.onActivityCreated(savedInstanceState)
    binding.addEditSave.setOnClickListener { listener?.onSaveClicked() }
}

The code does not show any errrors but it does not seem to create the listner. I have a Log.d in the onSaveClicked callback function and when I use the first (findViewById) version of the function it works (it calles onSaveClicked) but with the second version (using bindings) onSaveClicked does not get called when I click the Button.

I Cant figre out why the second version does not work, I thought the two versions of onActivityCreated should do the same thing.

The interface in AddEditFragment.kt is

interface OnSaveClicked {
    fun onSaveClicked()
}

Are you also initializing your binding? Generally you do this in onViewCreated(:). It usually looks like binding = FragmentAddEditBinding.inflate(layoutInflater). After you did that it should work correctly. — Robin
– Robin, Commented Oct 10, 2022 at 14:03

Sandesh Khutal · Accepted Answer · 2022-10-10 14:06:11Z

4

In fragment you should add your view in onCreateView or in OnViewCreated not in onActivityCreated

Please refer link for more details.

private var _binding: FragmentAddEditBinding? = null
// This property is only valid between onCreateView and
// onDestroyView.
private val binding get() = _binding!!

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    _binding = FragmentAddEditBinding.inflate(inflater, container, false)
    val view = binding.root
 binding.addEditSave.setOnClickListener { listener?.onSaveClicked() }
    return view
}

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

answered Oct 10, 2022 at 14:06

Sandesh Khutal

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Ben Edwards · Accepted Answer · 2022-10-14 15:37:09Z

0

OK, thanks for all the help. turned out I was doing the inflate wrong.

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        Log.d(TAG, "onCreateView")
        binding = FragmentAddEditBinding.inflate(layoutInflater, container, false)
        return binding.root
}

I was doing

binding = FragmentAddEditBinding.inflate(layoutInflater)

I missed out on the last 2 args as I was taking the code from the inflate when I am in an Activity, not a Fragment. I think it is to do with the layout effecticly being in the parent.

edited Oct 14, 2022 at 15:37

answered Oct 12, 2022 at 19:54

Ben Edwards

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