classifier does not have a companion object - android-studio

Question

i want to use BottomNavigationView in my app and i'm facing this problem with kotlin (never had it before with java) i see this message :
classifier 'listFragment' does not have a companion object and thus must be initialized here
this is my code :
private val mOnNavigationItemSelectedListener = BottomNavigationView.OnNavigationItemSelectedListener { item ->
when (item.itemId) {
R.id.listNav -> {
//the problem is here in listFragment word below
setFragment(listFragment)
return#OnNavigationItemSelectedListener true
}
R.id.accountNav -> {
//the problem is here also in accountFragment word below
setFragment(accountFragment)
return#OnNavigationItemSelectedListener true
}
false
}
private fun setFragment(fragment: Fragment) {
supportFragmentManager.beginTransaction().replace(R.id.mainFrame , fragment).commit()
}
any help is appreciated :)

Answer 1

i edited it this way and it worked :
private val mOnNavigationItemSelectedListener = BottomNavigationView.OnNavigationItemSelectedListener { item ->
when (item.itemId) {
R.id.listNav -> {
val mFragment = cartFragment.newInstance()
openFragment(mFragment)
return#OnNavigationItemSelectedListener true
}
R.id.cartNav -> {
val mFragment = cartFragment.newInstance()
openFragment(mFragment)
return#OnNavigationItemSelectedListener true
}
R.id.supportNav -> {
val mFragment = supportFragment.newInstance()
openFragment(mFragment)
return#OnNavigationItemSelectedListener true
}
R.id.accountNav -> {
val mFragment = accountFragment.newInstance()
openFragment(mFragment)
return#OnNavigationItemSelectedListener true
}
}
false
}
private fun openFragment(fragment: Fragment) {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.mainFrame, fragment)
transaction.addToBackStack(null)
transaction.commit()
}
fragments goes like this :
class listFragment : Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
inflater.inflate(R.layout.fragment_list, container, false)
companion object {
fun newInstance(): listFragment = listFragment()
}
}

Answer 2

If someone is struggling (like I was) with the error in the title produced in a when block,
when compared a sealed object, then don't forget the is keyword, like this:
when (someSealedClass) {
is SomeSealedClass.Foo -> ...
// ^^ don't forget this
}