Specification of JavaBean

(1) The JavaBean class must be a public class and set its Access property
(2) The JavaBean class must have an empty constructor: The class must have a public constructor with no parameters, and this constructor should also set the default value of the attribute by invoking the setting method of each attribute.
(3) A JavaBean class should not have a public instance variable, the class variable is private
(4) The holding value should be accessed through a set of access methods (GETXXX and SETXXX): For each attribute, there should be a dedicated instance variable with a matching public getter and setter method.

Specification of JavaBean