将可观察字段绑定到动态创建的视图

Question

我有一个有趣的问题。在我的代码中，我动态创建了一些RadioButtons并将其添加到RadioGroup。但是我无法理解如何使用mvvm和数据绑定而不使用xml以编程方式向每个RadioButtons添加可观察的布尔值...因此，例如，如果我们在xml静态中有RadioButtons，我们将拥有类似的东西：

<RadioButton
       android:id="@+id/someRadioButton"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:checked="@{viewModel.isChecked}"
       android:text="@string/some_string" />

和

ObservableBoolean isChecked = new ObservableBoolean(false);

在我们的代码中。但是，如果我们在xml中没有按钮却在代码中添加了按钮，那么如何添加可观察字段呢？喜欢

RadioButton radioButton = new RadioButton(this)
radioButton.text = localeLanguage.languageName
RadioGroup.LayoutParams params = RadioGroup.LayoutParams(RadioGroup.LayoutParams.MATCH_PARENT, RadioGroup.LayoutParams.MATCH_PARENT)
radioButton.layoutParams = params
return radioButton

Answer 1

请参见official doc。通过xxxBinding = DataBindingUtil.inflate(layoutInflater, R.layout.xxx, viewGroup, false);，然后是xxxBinding.checked = isCheked，您将获得xxxBinding。

Answer 2

您可以使用如下所示的LiveData：

ViewModel {
  val _radioCheckedLiveData = MutableLiveData<Boolean>()
  val radioCheckedLiveData: LiveData<Boolean> = _radioCheckedLiveData

  private fun setRadioChecked(checked: Boolean) = _radioCheckedLiveData.value = checked  

  // handle radio check event 
  fun radioChecked(checked: Boolean) {
  if (checked) {
   // do something and change the data source
  }

 fun xxxFun() {
   // if you want to change radioButton check status by code, no need to set RadioButton's status directly
   setRadioChecked(true)
 }
}

}

Activity {
  val radioButton = RadioButton(context)
  viewModel.radioCheckedLiveData.observe(this) {checked->
     radioButton.checked = checked == true
  }
  radioButton.setOnCheckedListener {checked->
     viewModel.radioChecked(checked)
  }
}