override fun onTextChanged()

in build-android-start/app/src/main/java/com/google/firebase/codelab/friendlychat/MyButtonObserver.kt [24:32]


    override fun onTextChanged(charSequence: CharSequence, start: Int, count: Int, after: Int) {
        if (charSequence.toString().trim().isNotEmpty()) {
            button.isEnabled = true
            button.setImageResource(R.drawable.outline_send_24)
        } else {
            button.isEnabled = false
            button.setImageResource(R.drawable.outline_send_gray_24)
        }
    }