Chipgroup OnCheckedChangeListener wrong chip-id

[Vivien Scholz]

I have a fragment where I display Chips at the top containing the names of categories and a recyclerview below containing all the ingredients. The Chips are dynamically created in the Category Observer. When a chip gets checked the recyclerview gets filtered to display the ingredients belonging to the choosen category.

The problem I have, is that when navigating up (pressing back) to go back to the previous fragment and then opening the fragment again, the OnCheckedChangeListener of the chipgroup returns the wrong chip id (in "p1"). Therefore I get a outOfBoundsException since there are only 9 children.

Example:
first run -> id: 1 (first item) -> correct
second run -> id: 19 (first item) -> false
third run -> id: 28 (first item) -> false
..and so on.

class BlankFragment2 : Fragment() {


    private var ingredientViewModel : IngredientViewModel? = null
    private var categoryViewModel : CategoryViewModel? = null
    private var adapter : IngredientAdapter? = null


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

        setHasOptionsMenu(true)

        ingredientViewModel = ViewModelProvider(activity!!).get(IngredientViewModel::class.java)

        categoryViewModel = ViewModelProvider(activity!!).get(CategoryViewModel::class.java)

        adapter = IngredientAdapter(context!!)



    }
    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        return inflater.inflate(R.layout.fragment_blank2, container, false)
    }

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

        (activity as AppCompatActivity).setSupportActionBar(bottombar)
        (activity as AppCompatActivity).supportActionBar!!.setDisplayHomeAsUpEnabled(true)


        setObserver(adapter!!)

        rvIngs.adapter = adapter
        rvIngs.layoutManager = GridLayoutManager(context, 2)



        chipgroup.setOnCheckedChangeListener { p0, p1 ->

            if(p1 != -1){
                adapter!!.filter.filter((p0[p1-1] as Chip).text)
            } else {
                adapter!!.filter.filter(null)
            }
        }

    }

    private fun setObserver(adapter: IngredientAdapter){

        ingredientViewModel!!.getIngs().observe(viewLifecycleOwner, Observer {
            adapter!!.setIngCopyList(it)
            adapter!!.submitList(it)
        })


        categoryViewModel!!.getCats().observe(viewLifecycleOwner, Observer {
            adapter.setCatCopyList(it)

            for (cat in it){
                val chip = layoutInflater.inflate(R.layout.chip_style, chipgroup, false) as Chip
                chip.text = cat.catName
                chip.isCheckable
                chip.isClickable
                chipgroup.addView(chip)
            }
        })

    }


    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
        inflater.inflate(R.menu.ing_bot_menu, menu)
        super.onCreateOptionsMenu(menu, inflater)
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        when (item.itemId) {
            android.R.id.home -> findNavController().navigateUp()
        }
        return super.onOptionsItemSelected(item)
    }

}

 

[Vivien Scholz]

Found the solution. The id is not realiable in my use case. But you can assign a tag or id with "chip.id", "chip.tag" and use that.