android: unusual way to start activity

In one activity I need to start another one but with one condition: if it was started before then it must be finished and started again. This activity show some information about system state (Theme.Dialog style) it also can start some services and so on. As far as I开发者_JS百科 know when I do startActivity(intent) then onResume() will be called (if activity was started before). Does anybody know how to do it?

That's precisely how it should work. If you need to adjust the values on-screen, put that code in onResume(). What may not be obvious from its name is that onResume() is called when the Activity is first created as well. It's always the last method called before an Activity becomes active.

use the NEW_TASK_LAUNCH flag in the startActivity() call. Read documentation http://developer.android.com/guide/appendix/faq/framework.html#4

In the manifest file, in the activity attributes, you have the attribute launch mode, which let you specify how the activity must be launched (http://developer.android.com/guide/topics/manifest/activity-element.html#lmode).

Take a look at the description to see which mode suits most your needs. Then when the activity is brought to front, you can restart your service by overriding the Activity.onResume() method.

In one activity I need to start another one but with one condition: if it was started before then it must be finished and started again

There is nothing that only does this. The closest is to have the combination of FLAG_ACTIVITY_CLEAR_TASK|FLAG_ACTIVITY_NEW_TASK, but that has other side effects, such as wiping out any other activities.

As far as I know when I do startActivity(intent) then onResume() will be called (if activity was started before).

Not by default. By default, a second instance of the activity is created.