Question

我是Kotlin的新手。这是我想在kotlin中将其转换的Java代码

public class FavouritesViewModel extends AndroidViewModel {

    private FavouritesDBHelper mFavHelper;
    private ArrayList<Favourites> mFavs;

    FavouritesViewModel(Application application) {
        super(application);
        mFavHelper = new FavouritesDBHelper(application);
    }
}

但是我在构造函数中遇到了编译时错误

编码我的尝试：

public class FavoritesDataViewModel:ViewModel{
    private lateinit var mFavHelper: DatabaseHelper
    private lateinit var mfav:ArrayList<Favorites>

    public constructor(application: Application): super(application){
        mFavHelper = DatabaseHelper(application)
    }
}

在super(application)处出错

谢谢

Answer 1

public class FavoritesDataViewModel:AndroidViewModel{
    private lateinit var mFavHelper: DatabaseHelper
    private lateinit var mfav:ArrayList<Favorites>

    public constructor(application: Application): super(application){
        mFavHelper = DatabaseHelper(application)
    }
}

这解决了我的问题，我使用的是AndroidViewModel而不是ViewModel

Answer 2

public class FavoritesDataViewModel(application: Application):AndroidViewModel(application){
    private var mFavHelper: DatabaseHelper
    private lateinit var mfav:ArrayList<Favorites>
    init{
       mFavHelper = DatabaseHelper(getApplication<Application>())
    }

    public constructor(application: Application): super(application){
        mFavHelper = DatabaseHelper(application)
    }
}

这将帮助您调用超级调用以传递参数，并更安全地访问应用程序实例以用于viewModel。并帮助您避免使用latinit属性。

在ViewModel实例类的构造函数中调用super：Kotlin

2 个答案: