Detect the first time an Activity is opened on this session

Question

I need to detect the first time an activity is called every time the user launches the app:

• App is launched
• Activity X is called for the first time
  • Do something
• Activity Y, Z are called many times
• Activity X is called again many times
  • Do nothing

... so "do something" has to be called only if the app was closed (or killed) and then be launched again.

Answer 1

I usually use static boolean variable inside the activity as a flag. Then, inside onCreate(), test the variable; if it's true, do something and flip the flag.

public class MainActivity extends Activity {
    private static boolean RUN_ONCE = true;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ...

        runOnce();
    }

    private void runOnce() {
        if (RUN_ONCE) {
            RUN_ONCE = false;

            // do something
        }
    }

    ...
}