Input/output to a text file through a GUI

Hello!

I have an issue with a project I have to do. I need to develop a Java program able to display some information found in a .txt file through a GUI in table form, and also allow the user to search for specific information in that database (the text file), like table row number (so only the row the user picks is displayed, not the entire database). Also, within the same GUI, the user has to be able to input new information which needs to be appended to the text file/database. So I need to read from and write to a text file through a GUI. I can use a maximum of 5 classes for this and I am struggling with it, if anyone could help. Thanks!