Question

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.

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

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

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);
}

This code gives a null point exception.

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

Thanks in advance.

Answer 1

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:

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

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

• 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());