Android: Resuming an activity without reloading

I have two activities, say Activity A and Activity B. Activity A is created when the application starts and then Activity B is being called from Activity A as follows:

Intent i = new Intent(A.this, B.class);
startActivity(i);

Activity B loads a Thread on its onCreate() and then when you click on Back, it will return to Activity A. This Thread is loading some images from a Database that is bein开发者_如何学JAVAg updated within Activity B as well.

How can I save the state of Activity B so that I can avoid reloading the Thread that I have in Activity B when I call it again from Activity A.

Create a singleton class which loads the images and caches them. Every time you launch Activity B check this singleton class for images. If not loaded then load them otherwise read from the cache

Move the database loading to a separate class and load from there.

You may want to check this question: Saving Android Activity state using Save Instance State

But consider that, depending on how long the Activity A takes and how much memory the device has left, Activity B could be killed before it returns.