android - 实时数据。无法分配给 ‘value’ : the setter is protected/*protected and package*/for synthetic extension

Question

我正在尝试使用 android documentation 中所述的 LiveData 实现 DB Observer .

只要我在 Kotlin 中编程，我就会将函数(最初用 Java 编写)适应它。

在尝试保存数据时，我发现了这个问题。

Cannot assign to ‘value’: the setter is protected/*protected and package*/ for synthetic extension in ‘<library Grade: android.arch.livecycle:livedata-core-1.1.1>’

有人遇到过这个问题吗？

这是我的代码:

ViewModel:

class ProfileViewModel: ViewModel() {

    object FirstName: MutableLiveData<String>()

    fun getCurrentName(): LiveData<String> {
        return FirstName
    }
}

Fragment

class ProfileFragment{

    private lateinit var model: ProfileViewModel

    // this is called onViewCreated. inputFirstName is an Edittext.
    override fun setUp() {
        model = ViewModelProviders.of(this).get(ProfileViewModel::class.java)

        val nameObserver = Observer<String> { firstName ->
            inputFirstName.text = SpannableStringBuilder(firstName)
        }

        model.getCurrentName().observe(this, nameObserver)
    }

    fun saveProfileData() {
        val firstName = inputFirstName.text.toString()
        model.getCurrentName().value = firstName
    }
}

Answer 1

正如@spkink 建议的那样:

替换

fun getCurrentName(): LiveData<String>

与

fun getCurrentName(): MutableLiveData<String>

错误是因为 setValue(T value) 在 LiveData 中是 protected (所以你不能调用它)而它是 public 在MutableLiveData.