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Android

Posted by Josh Gold
Josh Gold
12,207 Points

How to Preserve Program State Between Views

Here's the scenario:

  1. I have MainActivity.XML and one other view, let's call it SomeView.XML.
  2. I have an int someInt set = 0 in MainActivity.Java.
  3. Later in SomeView.Java is make a change so that this int someInt = 1

It seems, however, when I change between views, the state is not retained. In other words int someInt is once again = 0.

2 Answers

Josh Gold
Josh Gold
12,207 Points

SharedPreferences worked for me here, and even saves the integer for subsequent launches of the app.

This line obtains shared preferences, which contain the rank of the user:

         rank = getPreferences(MODE_PRIVATE).getInt("UserRank", rank);

This line saves user's rank to shared preferences:

        getPreferences(MODE_PRIVATE).edit().putInt("UserRank", rank).commit();
Josh Gold
Josh Gold
12,207 Points

I just got the latest edition of Android App Development for Dummies, which has a whole chapter on Shared Preferences. So hopefully that will help me better understand this topic.

Jon Kussmann
PLUS
Jon Kussmann
Courses Plus Student 7,254 Points
Jon Kussmann
Jon Kussmann
Courses Plus Student 7,254 Points

Even if you use the same variable names between activities, they will represent different "boxes" in memory. One will not affect the other.

If you want to pass an integer from one activity to another (from your SomeView activity to your MainActivity) then you can do so by using the putExtra method on the intent that you create to go from one activity to another.

Josh Gold
Josh Gold
12,207 Points

That sounds like a good idea... I've been reading about other options as well. I might try to use SharedPreferences to store the integer. Perhaps with Shared Preferences the int will even be retained if the Android device is powered off.