java - 如何在Android中初始化一个类并将对象传递给构造函数？

Question

我有以下类(class):

public class MovieViewModel extends ViewModel {
    private String query;

    public MovieViewModel() {
        MyFactory factory = new MyFactory(); //Pass the query in the constructor
        //other stuff
    }
}

在我的 MainActivity 中，我正在创建此类的一个对象，如下所示:

MovieViewModel model = ViewModelProviders.of(this).get(MovieViewModel.class);

如何创建 MovieViewModel 类的对象，同时初始化 query 字符串，以便将其传递到 MyFactory 构造函数？

Answer 1

您可以创建自定义工厂。

public class MovieViewModelFactory implements ViewModelProvider.Factory {
    private Application mApplication;
    private String mParam;


    public MovieViewModelFactory(Application application, String param) {
        mApplication = application;
        mParam = param;
    }


    @Override
    public <T extends ViewModel> T create(Class<T> modelClass) {
        return (T) new MovieViewModel(mApplication, mParam);
    }
}

现在你可以这样使用

MovieViewModel movieViewModel = ViewModelProviders.of(this, new MovieViewModelFactory(this.getApplication(), "param")).get(MovieViewModel.class);