Simple "Stateless" StateMachine

Lightweight transition validity checker for some Stateful entity

Usage

@Data
public static class Task implements Stateful<TaskState> {
    private TaskState state = TaskState.TODO;
}

public enum TaskState {
    BACKLOG, TODO, IN_PROGRESS, DONE, ARCHIVED
}

public static void main(String[] args) {

    //configuring the transitions
    StateMachine<TaskState, Task> taskStateMachine = new HashMapStateMachine<TaskState, Task>()
            .beginStates(EnumSet.of(TaskState.BACKLOG))
            .endStates(EnumSet.of(TaskState.ARCHIVED))
            .addStates(TaskState.values())
            .addTransition(TaskState.BACKLOG,   // source state
                    TaskState.TODO,             // target state
                    task -> true,               // provide extra validations on transition
                    task -> {},                 // what to do on success                            
                    task -> {});                // what to do on error
                                             

    Task task = new Task();
    taskStateMachine.move(task, TaskState.IN_PROGRESS);
}

Project state

Not tested, draft, just for fun