LiveData的微调适配器

Question

Is it possible to construct ArrayAdapter for Spinner from LiveData<List<T>> instead of normally List<T> ?

What is the best practice to bind a ViewModel's LiveData returned value to a Spinner ?

Answer 1

If It is exactly what do you mean, so:

class MyVM : ViewModel() {
  ...
  private val mSpinnerData = MutableLiveData<List<String>>()
  ...
  fun fetchSpinnerItems(): LiveData<List<String>> {
    //fetch data
    mSpinnerData.value = <some fetched list of Strings>
    return mSpinnerData
  }
}

And after in your activity/fragment:

class MyActivity : AppCompatActivity() {
  private lateinit var mViewModel: MyVM
  ...
  override fun onCreate(outState: Bundle?) {
    //initialize your view model here...
    mViewModel.fetchSpinnerItems().observe(this, Observer { spinnerData ->
      val spinnerAdapter = ArrayAdapter(this, android.R.layout.simple_spinner_item, spinnerData)
      mSpinner.adapter = spinnerAdapter
    })
  ...
}