README.md

automa

Automa is a Java library to easily create and use Finite State Machines.

For example, defining a finite state machine for a music player is as simple as defining plain enums for the states and the events like:

public enum PlayerState {
    STOP,
    PLAY,
    PAUSE
}

public enum PlayerEvent {
   STOP,
   PLAY,
   PAUSE
}

Then you can simply create the player Finite State Machine doing:

Automa<PlayerState, PlayerEvent> player = new Automa<PlayerState, PlayerEvent>(PlayerState.STOP);
player.from(PlayerState.STOP).goTo(PlayerState.PLAY).when(PlayerEvent.PLAY).andDo(new Runnable() {
    public void run() {
        // TODO: Play music
    }
});
player.from(PlayerState.PLAY).goTo(PlayerState.STOP).when(PlayerEvent.STOP).andDo(new Runnable() {
    public void run() {
        // TODO: Stop music
    }
});
player.from(PlayerState.PLAY).goTo(PlayerState.PAUSE).when(PlayerEvent.PAUSE).andDo(new Runnable() {
    public void run() {
        // TODO: Pause music
    }
});
player.from(PlayerState.PAUSE).goTo(PlayerState.PLAY).when(PlayerEvent.PLAY).andDo(new Runnable() {
    public void run() {
        // TODO: Resume music
    }
});
player.from(PlayerState.PAUSE).goTo(PlayerState.STOP).when(PlayerEvent.STOP).andDo(new Runnable() {
    public void run() {
        // TODO: Stop music
    }
});

The last step is to connect your event source to player to send it the events to handle:

if (userPressedPlay())       player.signalEvent(PlayerEvent.PLAY);
else if (userPressedStop())  player.signalEvent(PlayerEvent.STOP);
else if (userPressedPause()) player.signalEvent(PlayerEvent.PAUSE);