MainActivity.kt

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    initViews()
    initTabLayout()
    initRecycler()
}

private fun initViews() {
    tabLayout = findViewById(R.id.tabLayout)
    recyclerView = findViewById(R.id.recyclerView)
}

private fun initTabLayout() {
    for (category in categories) {
        tabLayout.addTab(tabLayout.newTab().setText(category.name))
    }
}

private fun initRecycler() {
    recyclerView.adapter = CategoriesAdapter(this, categories)
}