I have an app on the Google Play market. For various reasons that I won't bother going into, I have changed the type of some of my preferences. For example a preference type was an Integer and in the most recent version it is now a String. I imagine this isn't good practice but unfortunately I had to do it.
My concern is that when someone updates to the new version their app will crash as the preference types have changed. For this reason I would like to clear the preferences whenever the app is updated (again I realise not ideal!)
Is this possible?
The SharedPreferences.Editor
class has a clear()
function, what removes all your stored preferences (after a commit()
). You could create a boolean flag which will indicate if updated needed:
void updatePreferences() {
SharedPreferences prefs = ...;
if(prefs.getBoolean("update_required", true)) {
SharedPreferences.Editor editor = prefs.edit();
editor.clear();
/*....make the updates....*/
editor.putBoolean("update_required", false)
editor.commit();
}
}
And after that you need to call this in your main (first starting) activity, before you access any preferences.
EDIT:
To get the current version (The versionCode declared in the manifest):
int version = 1;
try {
version = getPackageManager().getPackageInfo(getPackageName(), 0).versionCode;
} catch (NameNotFoundException e) {
e.printStackTrace();
}
if(version > ...) {
//do something
}
EDIT
If you want to do some updating operation, whenever the version changes, then you can do something like this:
void runUpdatesIfNecessary() {
int versionCode = getPackageManager().getPackageInfo(getPackageName(), 0).versionCode;
SharedPreferences prefs = ...;
if (prefs.getInt("lastUpdate", 0) != versionCode) {
try {
runUpdates();
// Commiting in the preferences, that the update was successful.
SharedPreferences.Editor editor = prefs.edit();
editor.putInt("lastUpdate", versionCode);
editor.commit();
} catch(Throwable t) {
// update failed, or cancelled
}
}
}