keep the data in a variable of the first act after returning from the second act by the up button

I have the following problem, I have a list view in act1 that depends on a variable to load, when I finish my act2 or I go back by the back button of the android (bottom button) the value of the variable is maintained, but when I return using the back button of the application the value of the variable is zeroed

note: my list view is being loaded by the onResume method.