Should startActivity always run the started Activities onCreate?

Question

I have a main activity and a sub activity. The main activity starts the sub activity using startActivity, and passes an object in the intent. The sub activity reads the object out of the intent in its onCreate action. The sub activity updates the object, then returns to the main activity using startActivity, again passing the updated object back. However, the main activities onCreate function is not called, so the code it contains to read the passed object does not run.

Further investigation indicated that the main activity onPause event is firing, i.e. it is only paused when the sub activity runs, so when the sub activity starts the main activity again, it just onResumes.

Does anyone know if there would be any disadvantages if I moved my data restore/store activities to the onResume and onPause events? I'm not using the onCreate savedInstanceState, should I be?

How else do you pass a set of data items between Activities without using a database or those preferences? Should I be using a database? I have about 20 fairly individual data items.

Any help would be much appreciated,

• Frink

Answer 1

It is more likely calling onResume() or onStart() depending on the child activity and how much control it takes.

Look at this page about 3/4's down at the graph.

http://developer.android.com/guide/topics/fundamentals.html

The parent never gets destroyed so it wouldn't have to recreate it. It should just get paused. You can override onResume() and onStart() just as you would onCreate().

Edit: Is there anything given to the user in the subactivity? It sounds like you don't actually need an activity you just need a java class that you can call methods on.

Answer 2

Have a look at the Activity life cycle here.

Also, consider starting your sub-activity using StartActivityForResult.

Answer 3

I would check out the startActivityForResult() method rather than just startActivity()

That should give you a means to pass things back to the calling activity.

From http://developer.android.com/reference/android/app/Activity.html:

Sometimes you want to get a result back from an activity when it ends. For example, you may start an activity that lets the user pick a person in a list of contacts; when it ends, it returns the person that was selected. To do this, you call the startActivityForResult(Intent, int) version with a second integer parameter identifying the call. The result will come back through your onActivityResult(int, int, Intent) method.

Answer 4

Why don't you call startActivityForResult from the main activity and get the data back in onActivityResult ? This is the normal way to do it.