OnCreate Calls After OnPause in Android

Question

I am developing an app in which i have create three activities

• Main_Activity
• Second_Activity
• CustomView_Activity

Here is the process in which these Activties called:

• MainActivity calls Second_Activtiy and in OnCreate of Second_Activtiy I have created object of CustomView_Activity.
• In Main_Activity I have a button on a LinearLayout which onClick calls Second_Activity in Second_activity OnCreate i have to keep my Screen On and and declare other things like buttons layouts etc.
• In CustomView_Activity i have creates canvas and onCanvas i have draw a Rectangle.

• Now when my Second_Activity calls after Main_Activity and calling OnPause on pressing Power button my activity calls

  OnPause -> OnStop -> OnCreate -> OnResume -> OnRestart -> OnDestroy
  

  and when I press the power button to on the screen OnResume -> onCreate -> OnRestart calls.

Due to calling of OnCreate again and again my activity not performing tasks correctly.

Please anyone who can help??

Answer 1

when orientation changes again Oncreate is called. That is why your activity is not running correctly after the first time.

To fix this you have declare this in your Manifest file where the activity is declared:

android:configChanges="keyboardHidden|orientation" 

For android 3.0 and above

android:configChanges="orientation|screenSize|keyboardHidden"

When the app is in landscape and the phone is locked, then the app reorients to portrait and hence onCreate gets called again. To prevent this add the above line.

Answer 2

You should never rely on your task stack maintaining all the state you need. Instead, save your activity's state using onSaveInstanceState() and have each activity base its actions on this state or the intent passed to it. By designing your activity flow this way, the activities can be created / destroyed by the system at its will (usually based on memory needs) and your activities will be able to pick up where they left off.