我有一个简单的Android应用程序，这是改变文本和颜色的TextView取决于我添加了多少乘客。我想为每个国家创建一个密封类。
下面是当前应用程序的代码：

class MainActivity : AppCompatActivity() {
    private var counter = 0
    private val maxPassengers = 50
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        binding = ActivityMainBinding.inflate(layoutInflater)
        super.onCreate(savedInstanceState)
        setContentView(binding.root)
        binding.seats.text = counter.toString()

        binding.minusButton.setOnClickListener {
            counter -= 1
            checkAndSwitchState(counter)
        }

        binding.plusButton.setOnClickListener {
            counter += 1
            checkAndSwitchState(counter)
        }

        binding.resetButton.setOnClickListener {
            counter = 0
            it.visibility = View.GONE
            checkAndSwitchState(counter)
        }
    }

    private fun checkAndSwitchState(counter: Int) {
        if (counter == 0) {
            binding.minusButton.isEnabled = false
            binding.textView.text = binding.textView.context.getText(R.string.green_text)
            binding.textView.setTextColor(Color.parseColor("#00FF00"))
            binding.seats.text = counter.toString()
        }

        if (counter in 1 until maxPassengers) {
            binding.minusButton.isEnabled = true
            binding.textView.text = "Осталось мест: " + "${maxPassengers - counter}"
            binding.textView.setTextColor(Color.parseColor("#0000FF"))
            binding.seats.text = counter.toString()
        }

        if (counter >= maxPassengers) {
            binding.resetButton.visibility = View.VISIBLE
            binding.textView.text = binding.textView.context.getText(R.string.red_text)
            binding.textView.setTextColor(Color.parseColor("#FF0000"))
            binding.seats.text = counter.toString()
        }
    }
}

因此，问题是如何在密封类中的MainActivity外部使用绑定