Android Studio - How to create a back button on randomly selected strings?

I have an array of strings that I am displaying in my activity using a random number every time a button called Next is clicked. How do I create another button called Back, that simply displays the previously or last generated strings in the order they were randomly generated?. So that instead of clicking next to generate another string, I can click Back at any time to view all the previous strings one by one and then click Next again to continue the random selection.