How to display stuff that was entered before in a listViewer? Please Help

It’s simple and yet I am not able to figure it out. Stuff from three textInputs added to a listViewer and then display it even if you exit the app. Now first thing you guys would tell is to save it in a database. I tried to do that but it leads to an empty listViewer. I have checked the designing and I have put contrasting colors for the listViewer. This problem isn’t getting solved from my end.

Why not just use a stored variable @rockode?