Question

How do I call the functions provided by Activity class from a class that does not extend Activity? Theoretically, yes, if I don’t extend Activity I cannot directly use the functions provided by it. But is there a workaround provided for this? If not, are there replacements or alternative ways for these functions?

For example,
If my class extends Activity, I can call setContentView() to instantiate my layout xml file. But if my class extends some other class and doesn’t extend Activity, then I can use the LayoutInflater to do the task. But what about other functions like registerReceiver() ? How do I get the functionality of ‘registerReceiver()‘ from any other class , obviously I wouldn’t want every such class to extend Activity. Static access by “Activity.function_name” is also not possible as these functions are not static.

Certain services can be accessed from anywhere. For example ‘println()‘ or Log.e(),System functions can be called from anywhere, whenever needed. Is there a similar way for other critical functions?

Conclusion:

Pass Context to destination class. For accessing some functions however, type-casting the passed Context to Activity is required.

Both Changdeo’s and BT’s answers are correct.

Thanks.

Answer 1

Although I have not found any documentation explicitly stating why, in every case where I have ever needed to do this, simply passing the Activity‘s Context is sufficient.

For a Context called contextActivity passed into any function, the following will allow access to these member functions you require:

((Activity) contextActivity).<anyMemberFunction>

Or if you need these functions in multiple cases it might be simplest just to do the following:

Activity myActivity = (Activity) contextActivity;

From there you can access these Activity member functions whenever you like by using:

myActivity.<desiredFunction>;

As I mentioned, I have never found any case where this hasn’t worked, but also no solid documentation saying this will always work. This is the trick I have seen consistently used though. If anyone has more to add, please do.