NoteListActivity.kt

class NoteListActivity : AppCompatActivity() {
    companion object {
        private val TAG = this::class.java.simpleName
    }

    private val viewModel by viewModel<NoteListViewModel>()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_note_list)
        setSupportActionBar(note_list_toolbar)

        note_list_add_note.setOnClickListener {
            Log.d(TAG, "addNote button pressed")
            launchNoteDetailActivity(this)
        }

        val adapter = NoteListAdapter {
            launchNoteDetailActivity(this@NoteListActivity, it.noteId)
        }
        note_list_recyclerview.layoutManager = LinearLayoutManager(this).apply {
            orientation = LinearLayoutManager.VERTICAL
        }
        note_list_recyclerview.adapter = adapter

        viewModel.notes.observe(this, Observer {
            adapter.loadItems(it ?: emptyList())
            adapter.notifyDataSetChanged()
        })
    }

    private fun launchNoteDetailActivity(context: Context, noteId: String? = null) {
        val intent = Intent(context, NoteDetailActivity::class.java)
        noteId?.let {
            val bundle = Bundle().apply { putString(NoteDetailActivity.ARG_NOTE, noteId) }
            intent.putExtras(bundle)
        }
        context.startActivity(intent)
    }
}