``` val fab = findViewById(R.id.fab) as FloatingAc...

# announcements

[douglarek]

val fab = findViewById(R.id.fab) as FloatingActionButton?
        fab!!.setOnClickListener { view -> Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG).setAction("Action", null).show() }
        supportActionBar!!.setDisplayHomeAsUpEnabled(true)

what does !! mean ?