A JavaBean provides a get and a set method for all its publicly exposed properties. If a property is read-only, the set method is omitted. Normally, JavaBeans also have a visual representation both on the toolbar and on the screen at runtime.
A2:
The SimpleBeanInfo class provides a getIcon() method that can be called by GUI tool to obtain an icon for its toolbar.
A3:
A bound property is one that can accept a listener who will be notified when the property value changes.
A4:
A constrained property is one that can also accept a listener. In addition, it provides the listener with a veto over the changes.