调用 super throws "super is not an expression"

Question

我从 Google 指南开始学习实现 MVVM： https://codelabs.developers.google.com/codelabs/android-room-with-a-view/#8（发布 link 特别是我感兴趣的页面）。
因为我了解在 Java 中实现它，所以我决定切换到 Kotlin。在 class 中初始化构造函数时扩展 AndroidViewModel 我需要调用 super 并且它会抛出以下错误：

"super' is not an expression it can only be used on the left-hand side of a dot ('.')"

当我用谷歌搜索并找到类似的但我完全不理解所以我没有解决我的问题。这是我 ViewModel class:

的代码

 class NotesViewModel private constructor(application: Application) : AndroidViewModel(application){

    var mRepository: NotesRepository? = null
    var mAllNotes: LiveData<List<Notes>>? = null

    init {
        super(application) // <-- here it throws me an error
        mRepository = NotesRepository(application)
        mAllNotes = mRepository!!.getAllWords()
    }

    fun getAllNotes(): LiveData<List<Notes>>{
        return mAllNotes!!
    }

    fun insert(notes: Notes){
        mRepository!!.insert(notes)
    }

}

那么，我该如何正确调用super，构造构造器呢？这是此 class:

的正确 java 代码

public class WordViewModel extends AndroidViewModel {

  private WordRepository mRepository;
    private LiveData<List<Word>> mAllWords;

    public WordViewModel(Application application) {
        super(application);
        mRepository = new WordRepository(application);
        mAllWords = mRepository.getAllWords();
    }

    LiveData<List<Word>> getAllWords() {
        return mAllWords;
    }

    void insert(Word word) {
        mRepository.insert(word);
    }
}

Answer 1

你已经在这里调用了 super : NotesViewModel private constructor(application: Application) : AndroidViewModel(application)

另一个问题是你的构造函数是private

只需将其设为 public 并从 init()

移除 super 调用

调用 super throws "super is not an expression"

Call super throws "super is not an expression"

java

android

mvvm

kotlin

android-livedata