Question

I have an application that navigates to the same activity but each time the activity loads with different parameters. In my application it’s a parsed data content retrieved from url. First thing I want to ask: When I push the backbutton of my device I get my earlier activity without being recreated. Is the objects in this activities alive and can I reference them?

Second question is if my first question doesn’t make sense, what do you advice me to do?

Answer 1

If you look at the Activity life cycle, you’ll notice that as long as your phone has enough memory, your first activity is kept in memory, and with it any member with the data it contains.

But if your phone needs to have some memory, it can kill any activity kept in background (any activity but the one being shown to the user), which means that you’ll loose any data that was in your first activity.

To know which happened, keep in mind that the onResume() method will always be called when your activity is brought to foreground (either on creation, or when you navigate back to it), but onCreate() will be called only when your application is created from scratch (meaning you don’t have any saved data).

You should use the bundle mechanism to save data when your activity is paused, and load it when you come back to it. Read the paragraph about Saving Activity state in Android doc to see how to use this.