classifier does not have a companion object

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()
}

}