如何检查是否正在打开应用-Android Studio

Question

I'm making a game and am saving data for the player using sharedPreferences. The way I have it set up right now, every time the main application (the first page) is loaded, the old data it held before is loaded. So, imagine a player has 100$, and they exit the app. Upon opening the app again, this data will be loaded and everything seems fine.

The problem, however, is that if a player's money is changed in ANOTHER activity, the way I have it set up right now is that any time a player navigates back to the main activity, the data is loaded. So if the player has $100 on the main activity, this info is saved every few seconds on the main activity. If the player spends 50$ on a second activity, when they return to the main activity, since the last saved data the main activity has is $100, it will load the $100.

This is a problem, and a way to fix it is to ONLY LOAD THE DATA WHEN THE APP IS OPENED. So like I don't want to load the data every time the player navigates to the main activity, but only when they open the app. I need a simple if() boolean statement to do this, but I'm not sure what the statement I need is.

Thanks!

Answer 1

Store a boolean in sharedPreferences and check if it exists or if it's false/true in the create of the activity, such as storing a value for "hasLoaded" with a value of either true or false . check this value in onCreate and then do your logic accordingly.

OR alternatively,

create a static variable in your mainActivity for hasLoaded , then in onCreate, do everything you want to do and then change it to true.

static boolean hasLoaded = false;

if(!hasLoaded){
//all your logic here
hasLoaded = true;
}

note: storing it in sharedPrefs will ensure that your initialization will only happen ONCE for all usages of the app, while storing it in a static variable will make sure it only happens once PER RUN of the app