Design Patterns and Best Practices in Java

Implementation

The visitor pattern defines a set of operations in a single class: it defines one method for each type of object from the structure it has to operate on. Adding a new set of operations can be done simply by creating another visitor. The class diagram is as follows:

The visitor pattern is based on the following classes:

• Element: This represents the base class for the object structure. All the classes in the structure are derived from it and they must implement the accept(visitor: Visitor) method.
• ConcreteElementA and ConcreteElementB: These are concrete classes to which we want to add external operations implemented in the ...