我有一个工作的应用程序，它做一些算术功能，这是超出了问题的范围，然后我想添加更多的功能，所以我把布局分为活动和片段，以便稍后添加其他片段，将做额外的功能。
然而，当我将带有一些按钮的布局与TextView（R.id.Result）沿着分离到新片段时，TextView的text属性仍按预期更新，但显示保持不变，始终显示在创建时最初分配给它的初始化值。
我确认对象与我预期的相同，在运行时期间通过logcat验证，我需要OFC的是在我更改TextView显示的text属性时更新TextView显示，从按钮正确调用numberInsertAction并发送正确的数据。

• 重要提示：下面只是代码的相关部分，它要大得多，我知道您在下面看到的内容可以简化，但它是这样构建的，因为下面没有显示其他类和功能，如果您需要查看或询问下面代码以外的内容，请进行，但我再次只包括相关部分，并删除了业务功能。*

先谢谢你。
只是重申一下：数字插入操作（查看：View）是由片段上的按钮调用的入口点/函数。
MainActivity.kt

class MainActivity : AppCompatActivity(), AddObserverToActivity {
    private lateinit var binding: ActivityMainBinding
    private lateinit var stateManager: StateManager

    override fun onCreate(savedInstanceState: Bundle?) {
        //initialize layout
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        val activityRoot = binding.root
        setContentView(activityRoot)

        stateManager = StateManager()
    }

    override fun addResultObserver(observer: Observer) {
        Log.d(TAG, "addObserver! ${observer.toString()} ${observer::class.toString()}")
        StateManager.addDisplayObserver(observer)
    }

    fun numberInsertAction(view: View) {
        if (view is Button) {
            StateManager.enterDigit(view.text.toString())
        }
    }
}

CalculatorFragment.kt

class CalculatorFragment : Fragment() {

    companion object {
        fun newInstance() = CalculatorFragment()
    }

    private lateinit var binding: FragmentCalculatorBinding
    private lateinit var mainActivityHandle: AddObserverToActivity

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        Log.d(TAG, "onCreateView")
        binding = FragmentCalculatorBinding.inflate(inflater, container, false)
        return inflater.inflate(R.layout.fragment_calculator, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        Log.d(TAG, "using on view created")

        mainActivityHandle = context as AddObserverToActivity
        Log.d(TAG, "${binding.Result} ${(binding.Result)::class.simpleName.toString()}")
        Log.d(TAG, mainActivityHandle::class.toString())
        mainActivityHandle.addResultObserver(DisplayPanel(binding.Result))

    }
}

StateManager.kt

class StateManager : Observable() {
    private val displayBuffer = DisplayBuffer(DecimalVariable("0"))

    fun enterDigit(digit: String) {
        Log.d(TAG, "enterDigit: $digit, $currentState")
        displayBuffer.insertDigit(digit)
    }

    fun addDisplayObserver(observer: Observer) {
        Log.d(TAG, "addDisplayObserver: $observer")
        displayBuffer.addObserver(observer)
    }

    private fun doNotify(Notified: Any) {
        Log.d(TAG, "doNotify: $Notified")
        setChanged()
        notifyObservers(Notified)
    }
}

DisplayBuffer.kt

class DisplayBuffer(initializationValue: SomeClass) : Observable() {
    private var initialValue = initializationValue
    private var resultString = "0"

    var value = initialValue
        set(value) {
            Log.d(TAG, "setter: $value")
            field = value
            doNotify()
        }

    fun set(value: String) {
        Log.d(TAG, "set: $value")
        this.value = value as Int
    }

    private fun doNotify() {
        Log.d(TAG, "doNotify")
        setChanged()
        notifyObservers(value.toString())
    }

    fun insertDigit(digit: String) {
        Log.d(TAG, "insertDigit: $digit result: $resultString")
        resultString = resultString + digit

        Log.d(TAG, "new value: $resultString")
        setChanged()
        notifyObservers(resultString)
    }
}

DisplayPanel.kt

class DisplayPanel(calculationTextView: TextView) : Observer {
    private val displayField: TextView = calculationTextView
    private val maxDigits = 16

    private fun setDisplay(text: String) {
        Log.d(TAG, "setDisplay: $text")
        if (text.length <= maxDigits) {
            displayField.text = text
            //displayField.invalidate()
        }
    }

    override fun update(observable: Observable?, targetObjects: Any?) {
        Log.d(TAG, "update: $this $observable, $targetObjects")
        setDisplay(targetObjects as String)
    }
}