In Java, the GUI (Graphical User Interface) is built hierarchically in terms of Components -- one Component nested inside another starting with the smallest Buttons, including Menus, TextFields etc. and ending with full Window divided into Frames, MenuBars etc. |
The placement of components in the window is controlled in a fairly high-level way by one of several Layout Managers. |
The user can interact with the GUI on many of its components, by clicking a button, typing in text, etc. These actions cause an Event to be generated, which will be reported by the system to a class which is an Event Listener, and which will have an event handler method for that event. This method will provide the appropriate response to the user's action. |