Android application loses state after launching another intent

Question

So I have the following:

A Common class that many of my Activities access in my android application, via setting the class in my manifest:

<application android:name="com.dev.games.phraseparty.Common"... />

Now, within this class I have several objects that are constructed to preserve application state and common services to perform applications that are constructed in the Common constructor

ie

GameStateVO gameState;

public Common()
{
    gameState = new GameStateVO();
}

My problem is that my Activity has an Admob ad. When the user clicks on the ad, it calls the webbrowser intent to open the ad URL in a webbrowser.

Now, when I click back from the webbrowser launched by admob, it takes me back to the caling activity and the OnCreate method is called.

This activity then gets a null pointer exception because it will do something like:

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Common common = this.getApplication();

//null pointer here since the game state VO is null since the Common has lost its state.
int score = common.getGameState().getScore();

}

It sounds like your app is undergoing a hard kill. You may want to persist the state on a hard kill in onStop say to prefs. You can do this by using a flag isSavedInstanceState. Set this to false in onResume and to true in onSaveInstanceState. Then in onStop write to prefs if (!isSavedInstanceState). Read in from prefs in onCreate if the bundle in onCreate == null. — JAL, May 17 '11 at 06:17

score 1 · Answer 1 · answered May 17 '11 at 02:25

If you have no active foreground activity, then your process is ripe for shutdown by the OS to obtain more resources. The browser app in particular i've noticed uses a lot of resources and can quickly lead to background activities and later processes being killed off. Having a service can help keep your process around, but even then it can still be killed off if needed. I think you'll need to use the activity lifetime cycle method to save & restore your state. See the process lifecycle section of the docs for more info

But what about data stored in the Application class? – neteinstein May 18 '11 at 16:02 — neteinstein, May 18 '11 at 16:02

score 1 · Answer 2 · edited May 23 '17 at 12:26

1

You might want to look into implementing the onSaveInstanceState method: this lets you store any relevant information before it gets killed off. See http://developer.android.com/reference/android/app/Activity.html#onSaveInstanceState%28android.os.Bundle%29 for the actual call you need to implement, and Saving Android Activity state using Save Instance State for a quite excellent example.

edited May 23 '17 at 12:26

Community

1
1

answered May 17 '11 at 02:28

Femi

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Thank you for your help. I am now saving state and restoring in my oncreate method and no more crashes. – Logan May 17 '11 at 19:09

Android application loses state after launching another intent

2 Answers2

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