tsm4j

A tiny, in-memory, zero dependency state machine library

Install

Gradle

implementation 'com.tsm4j:tsm4j:1.1.0'

Maven

<dependency>
    <groupId>com.tsm4j</groupId>
    <artifactId>tsm4j</artifactId>
    <version>1.1.0</version>
</dependency>

Usage

Example

An example of defining and running a state machine:

StateMachine<TestState> stateMachine = StateMachineBuilder.from(TestState.class)
    .addTransition(TestState.HUNGRY, TestState.MAKE_FOOD)
    .addTransition(TestState.MAKE_FOOD, TestState.FOOD_IS_READY)
    .addTransition(TestState.FOOD_IS_READY, TestState.EAT_FOOD)
    .addTransition(TestState.EAT_FOOD, TestState.FULL)
    .build();

assertThat(stateMachine.send(TestState.HUNGRY).reached(TestState.FULL)).isTrue();

You can bind a listener which is called whenever some state(s) is reached

StateMachine<TestState> stateMachine = StateMachineBuilder.from(TestState.class)
    .addTransition(TestState.NO_FOOD, TestState.MAKE_FOOD)
    .addListener(TestState.MAKE_FOOD, context -> {
        System.out.println("making food...");
        context.queue(TestState.FOOD_IS_READY);
    })
    .addListener(debugLoggingListener())
    .build();

assertThat(stateMachine.send(TestState.NO_FOOD).reached(TestState.FOOD_IS_READY)).isTrue();

More Examples

see tsm4j/test.

About the older version

In short, it was going in the wrong direction, we should separate state machine from action.

Contributing

Feel free to open up an issue for a feature request, bug report, or pull request.