java - 可以使用哪些不同类型的上下文来代替 Activity ？

Question

我正在阅读 admob 中介文档，我看到了这个，但我很困惑，因为我认为当你使用“这个”时，它指的是你正在进行的 Activity 。它说他们建议传递一个 Activity 实例，例如下面。我认为这是唯一可能的方式，有没有人知道我将传递的上下文的示例，而不是我当前的 Activity ？

adView = new AdView(this);

Answer 1

"I was reading through admob mediation documentation and I seen this but im quite confused, because I thought when you use "this" it is referring to the activity you are in."

你有点不对。 this 指的是您当前的对象。来自Java documentation :

Within an instance method or a constructor, this is a reference to the current object — the object whose method or constructor is being called. You can refer to any member of the current object from within an instance method or a constructor by using this.

例如，匿名类中的this会引用对象类:

View view;
view.setOnClickListener(new View.OnClickListener() {
        @Override public void onClick(View v) {
          // this will refer to View.OnClickListener object.
        }
      });

---

I thought this was the only possible way does anyone know an example of what would be a context I would pass in thats not my current activity ?

您还可以在 Application 类中创建 AdView，但我从来不推荐这样做:

public MyApp extends Application {
  private AdView mAdView;

   ...
   public void createAdView() {
     // this will refer to MyApp which is a context.
     mAdView = new AdView(this);

     ...
     // the rest is history
   }
}

或者有人会创建一个 Util 来生成 AdView 但忘记将 Context 限制为仅 Activity:

public AdUtil {
  private AdUtil(){}

  ...

  // Here the parameter context can be Application, Activity, etc.
  public static AdView createAdView(Context context) {
    AdView adView = new AdView(context);

    ...
    return adView;
  }
}