How to use getSystemService in a non-activity class?

Solution 1:

You can pass the context to the non-activity class which is the preferred way or you could encapsulate the base context of the application to a singleton which would allow you to access the context anywhere within the application. At some cases this might be a good solution but in others its certainly not a good one.

Anyway, if you want to trigger an alarm via the AlarmManager I'm pretty sure the alarm should inherit from a Service or better yet from IntentService and in such cases you have access to the context via this.getBaseContext() or this.getApplicationContext()

Solution 2:

Service and Activity inherit from Context - so when you are calling getSystemService in these classes, you are really calling super.getSystemService.

If you want to have a Context available in another class, you can pass one as an argument to a method of that class, keep a reference to it, etc.

Edit: Code sample. But seriously, it is extremely basic - if you understand inheritance and methods.

class MyActivity extends Activity { // Activity extends Context, so MyActivity also extends Context
  void someMethod() {
    MyOtherClass.useStaticContext(this);
    MyOtherClass instance = new MyOtherClass();
    instance.useInstanceContext(this.getApplicationContext());
  }
}
class MyOtherClass {
  static void useStaticContext(Context context) {
  }
  void useInstanceContext(Context context) {
  }
}