Using Java Enums to Implement Concurrent-Hierarchical State Machines

A systematic review of code generation proposals from state machine specifications

“…This proposal normally uses doubly nested switch statements for partitioning the event-handler function to segments reflecting the object behaviour in specific states (external branches) and sub-segments for each event handled in the state (internal branches) [46,47,57,63]. As stated in [11], this technique works well when implementing flat state machines and is mostly used in non-object-oriented procedural languages. An example of this method's use can be seen in the work presented by Metz et al [S18], where an ordinary switch statement in C++ is used to perform the state transition process of the system.…”

“…aims to provide an easy way for implementing concurrent/hierarchical state machines into efficient and encapsulated Java code based mainly on the use of Java Enums [77], making the resulting code compact, efficient and easy to understand [11,38]. His approach considers state machines having hierarchical and concurrent states, and encapsulates the state machine behaviour within a specific class and keeps the structure of the state machine obvious at the programming level.…”

“…At this point, it is well known that the software industry does not always provide satisfactory solutions to fill the gap between high-level modeling languages and programming languages. In particular, generating code from state machine diagrams constitutes one of the most challenging tasks due to their dynamic nature and because many of the state machine specification concepts are not directly supported by the object-oriented programming languages [6][7][8][9][10][11] (such as events [8], states [8,7], history pseudostates [8], or fork pseudostates [7]). Therefore, it is not surprising that there are a wide number of proposals in the literature devoted to studying the implementation of state machine specifications in different programming languages in a wide variety of application contexts such as distributed control systems [12], decentralization of production control systems [13,14], e-voting systems [15][16][17], or even NASA space missions [18][19][20].…”

Automatic Code Generation From UML State Chart Diagrams

“…The above mentioned methods failed to represent the concurrent states. Some literature, based on State Design Patterns, attempted to address this issue but resulted in very complex design patterns [24], [27], and failed to implement the key features of state machine. For example, in Spinke [24], it requires 17 classes in the implementation for representing a state machine with 6 states and 6 events.…”

“…Ali [27] presents the implementation of concurrent and hierarchical state machines by making use of enumerators in Java language. It proposes a Java implementation pattern for state machines.…”