通过静态方法访问共享preferences [英] Accessing SharedPreferences through static methods

问题描述

我的共享preferences存储的一些信息。我需要从（从领域模型类）访问outsite的活动信息。所以，我创建了一个活动，我只用它来获取共享preferences的静态方法。

I have some information stored as SharedPreferences. I need to access that information from outsite an Activity (in from a domain model class). So I created a static method in an Activity which I only use to get the shared preferences.

这是给我一些问题，因为显然它不可能调用从静态方法的方法getShared preferences。

This is giving me some problems, since apparently it is not possible to call the method "getSharedPreferences" from a static method.

这里的消息日食是给我：

Here's the message eclipse is giving me:

Cannot make a static reference to the non-static method 
getSharedPreferences(String, int) from the type ContextWrapper

我试图解决这个通过使用活动实例，像这样的：

I tried to work around this by using an Activity instance, like this:

public static SharedPreferences getSharedPreferences () {
  Activity act = new Activity();
  return act.getSharedPreferences("FILE", 0);
}

这code给出零点例外。

This code gives a null point exception.

有一个变通？我是不是要去参加一个android- code-气味试图做到这一点？

Is there a work-around? Am I going into an android-code-smell by trying to do this?

在此先感谢。

推荐答案

这是因为在这种情况下，的行为是您只需创建一个对象。你必须让机器人为你做的; getShared preferences（）是上下文的方法，（活动，服务和其他类从上下文扩展）。所以，你必须做出选择：

That's because in this case, act is an object that you just create. You have to let Android do that for you; getSharedPreferences() is a method of Context, (Activity, Service and other classes extends from Context). So, you have to make your choice:

• 如果该方法是上下文的活动或其他类型的内部：

• If the method is inside an activity or other kind of context:

getApplicationContext().getSharedPreferences("foo", 0);

如果该方法是上下文的活动或其他类型外：

If the method is outside an activity or other kind of context:

// you have to pass the context to it. In your case:
// this is inside a public class
public static SharedPreferences getSharedPreferences (Context ctxt) {
   return ctxt.getSharedPreferences("FILE", 0);
}

// and, this is in your activity
YourClass.this.getSharedPreferences(YourClass.this.getApplicationContext());

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