startActivity on Android

Question

Hello, so i've been trying to get my application to run an Activity via an intent and it works fine, when i then assign the finish(); method, it returns to the activity that called it. The only thing i don't understand is that i'm not sure if the callee Activity is put onPause while the called Activity is in-front. I've tried to setup a toast message in the onPause() method of the callee Acitivty but it won't appear.

I first tried to call the second Activity with startActivity(intentname) and then a finish() method on the first Acitivty, i then tried to use the startActivityForResult() (even though i don't really need to recieve any information from the called Activity) method and closed it with onActivityResult().

I can't find any information about the side-effects that these Activity methods has on a Activity that's calling another. So i'm wondering if anybody could help me out ?

//Thx in advance

Answer 1

According to the documentation for Activity, the onPause() lifecycle method WILL be called when another Activity is put in front of it.

http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle

If the called Activity is is semi-transparent, then onStop() will also be called, but if your initial Activity is not visible at all, onStop() will not be called.

It is also of worth to note that when you call finish() on the called Activity, the onResume() will be called on the caller (and onStart(), assuming onStop() was also called)

Answer 2

To quickly answer your question: if activity A starts activity B, then A's onPause method is run. I think there might be an exception if B isn't full screen, but that's only a tentative memory from something I read in the documentation a while ago.

As for why your toast wasn't showing - did you remember to .show() it? I always used to forget to do that. Toasts can also get missed if they're triggered just as the activity is pausing, since its context goes away. There's a much easier way to test it - just use the Log method. For example, Log.d("My app name", "onPause was just triggered"); The purpose of the "My app name" string is to let you filter by it in LogCat. If you don't know how to display LogCat, and assuming you're using Eclipse, see this answer to another question.

Answer 3

got it to work , was a bit confused of the purpose with onResume(), i was suppose to decleare a onActivityResult() in the first Activity so that the second Activity would return to it right after finish()