LiveData.无法分配给'value':setter受保护/*受保护,package*/用于合成扩展

Question

我正在尝试使用Android文档中描述的LiveData实现DB Observer .

只要我在Kotlin编程,我就会调整函数(最初用Java编写).

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>’

有人有这个问题吗？

这是我的代码:

视图模型:

class ProfileViewModel: ViewModel() {

    object FirstName: MutableLiveData<String>()

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

分段

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:

更换

fun getCurrentName(): LiveData<String>

同

fun getCurrentName(): MutableLiveData<String>

这个错误是因为造成setValue(T value)是protected在LiveData(所以你不能把它),而这是public在MutableLiveData.