Why is the UI not showing up in my code below:
public class GUI extends JPanel{
public GUI(String name, String address, List reviews, Icon
Panels just don't show up in Swing. They have to be added to windows. Create JFrame or JDialog and add your panel to it.
I guess JPanel cannot be a toplevel container. It has to be put inside a JFrame or JWindow to be shown
JFrame f=new JFrame();
f.add(test);
f.setVisible(true);
A JPanel isn't a top level container. You need to place that JPanel in a JDialog or JFrame. Make sure to add it to the content pane of that dialog or frame:
JFrame f = new JFrame();
f.getContentPane().add(test);