无法在Activity中实例化ViewModel [英] ViewModel cannot be instantiated in an Activity

问题描述

我正在尝试实例化一个ViewModel以便在我的所有Activity中使用.

I am trying to instantiate one ViewModel to use across all of my Activity(s).

public class LaunchActivity extends Activity {
    private Controller control;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_launch);
         control = ViewModelProviders.of(this).get(Controller.class);
    }
}

但是在 control = ViewModelProviders.of(this)<-时出现错误，指出它无法解析 of(this)，但基于示例Android开发人员在实现ViewModel的此处；扩展ViewModel的类应该可以在Activity上实例化，对吗?

but I got an error at control = ViewModelProviders.of(this) <-- stating that it cannot resolve of(this), but based on the example here by Android Developer on Implementing ViewModel; a class that extends ViewModel should be able to be instantiated on Activity, am I right?

如果我在做什么是错误的，我应该如何为我的Activity实例化一个ViewModel对象?因为 ViewModelProviders.of()仅适用于Fragment，我是否必须用Fragment创建 n 个活动?

If what I am doing is wrong, how should I instantiate a ViewModel object for my Activity(s)? Do I have to create n number of Activity(s) with Fragment(s) since ViewModelProviders.of() only works with Fragment?

推荐答案

您需要使用支持库活动.

AppCompatActivity 或 FragmentActivity

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