Sending an Activity to a non-Android class

I'm pretty much a noob when it comes to Android development. I have an Activity that has a method that pretty much just sets the text of a TextView to whatever text is provided as an argument. I have a second class, which is a Runnable, and I want to be able to give it the Activity (or obtain the Activity somehow), so it can call said method when it needs to.

This Runnable will eventually connect with a server, so it can update the application with information from the server. I've done client/server Java stuff before, so that's not the issue. I just need to figure out how to communicate between this Runnable and the Activity.

Originally, I was going to just pass the Activity itself in, but I read that it would create problems if I did. Instead, I was supposed to pass in an ApplicationContext via getApplicationContext(). I did that, but now I don't know what to do with the ApplicationContext. I tried casting it to the my Activity class, but the program just crashes.

开发者_如何学编程How do I accomplish what I'm aiming at?

There are a few specific ways in Android to handle threading like AsyncTasks etc., you should read up on how to do 'painless' threading here. If it's just a one-off task where you connect to the server, get the value, set it in the TextView and then finish, I think an AsyncTask would be your best option. Continuing background processes are more suited to being services.

you can pass your activity to the constructor of your second Class like this :

public SecondClass(YourActivity _yourActivity){
this.activity = _yourActivity;
//do stuff
}

and in your Activity , you can instanciate your class like this :

SecondClass instance = new SecondClass(this);

NOTE : in your SecondClass , if you want to change the UI of your application , you can use the method runOnUiThread(Runnable);