Okay, so what i'm trying to do is, when i click on setting. it will go to my settings panel. the information just display accordingly. But when i go back to summary panel, the name just literally disappeared. When i click back the settings the information has also disappear after retrieving..
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It will be not possible to help you trace your code since you have only posted partial codes. I will guide you to find your problem, not look at your codes and help you debug.
Before you enter your Settings and Summary Panel in the respective constructors, print out into STDOUT and find out the values inside the UserData object. It will help you to trace certain logic flows in your constructors.
You will also need to answer if your Settings and Summary Panels are created each time they are displayed or set to be visible. Remember your constructors are only involved each time the object is instantiated, not every time it is drawn on the screen.
I will also recommend you to rename your MainPanel as BasePanel, or AbstractPanel because these conventions denote the hierarchical modelling. MainPanel is more likely interpreted as you have a main dashboard UI somewhere when your program starts.