Finite State Machine pattern

[stephen-lazarionok]

Description:
The Finite State Machine (FSM) design pattern is a behavioral design pattern used to model the behavior of a system that can be in one of a finite number of states. The system transitions from one state to another in response to external events or internal actions. This pattern is useful in scenarios where an object’s behavior is dependent on its state, and the state can change in response to events.

Main elements of Finite State Machine pattern:

1. States: Define the possible states the system can be in.
2. Transitions: Define the rules or conditions that trigger a change from one state to another.
3. Events: Actions or occurrences that cause state transitions.
4. Context: Maintains the current state of the system and facilitates state transitions.
5. State Interface: Defines the behavior associated with each state. Each state implements this interface to define its specific behavior.

References:

• State Design Pattern - Refactoring Guru
• State Machines - Martin Fowler
• GitHub Contribution Guidelines

Acceptance Criteria:

1. Implement the FSM pattern with at least three distinct states and the transitions between them.
2. Create a context class that maintains the current state and handles state transitions based on events.
3. Provide example scenarios demonstrating the FSM pattern, including state definitions, transitions, and event handling.

[iluwatar]

Hi there @stephen-lazarionok ,

I am aware of the State pattern but unfamiliar with the FSM. Can you point the source of the pattern, web link or some book maybe?

[stephen-lazarionok]

Here is the information about FSM:
The description of the pattern
FSM in Erlang - very nice explanation
The implementation of FSM in Akka

[iluwatar]

Thank you for the links. Especially the first explains the pattern well. We'll accept the pattern once you make the pull request.

[stephen-lazarionok]

Initial pull request is ready - Finite state machine #222. I will add the documentation later as well as include this module to the parent pom.xml later.

[amit2103]

@iluwatar Can I work on this?

[iluwatar]

@amit2103 Yes, I will change the labels