Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference code example

Example: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference

val toolbar = findViewById<MaterialToolbar>(R.id.main_toolbar)
        setSupportActionBar(toolbar)