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August 23, 2016 16:59
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state machine example implementation in Java
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package com.adambene.gist; | |
import static com.adambene.gist.ThreadStateMachine.Transition.CREATE; | |
import static com.adambene.gist.ThreadStateMachine.Transition.FINISH; | |
import static com.adambene.gist.ThreadStateMachine.Transition.RESUME; | |
import static com.adambene.gist.ThreadStateMachine.Transition.WAIT; | |
import java.util.logging.Level; | |
import java.util.logging.Logger; | |
public class ThreadStateMachine | |
{ | |
private static Logger LOGGER = Logger.getLogger(ThreadStateMachine.class.getName()); | |
public static enum State | |
{ | |
NEW | |
{ | |
@Override public State next(Transition transition) | |
{ | |
return (transition == CREATE) ? RUNNING : ILLEGAL; | |
} | |
}, | |
RUNNING | |
{ | |
@Override public State next(Transition transition) | |
{ | |
if (transition == WAIT) | |
{ | |
return BLOCKED; | |
} | |
else if (transition == FINISH) | |
{ | |
return DEAD; | |
} | |
else | |
{ | |
return ILLEGAL; | |
} | |
} | |
}, | |
BLOCKED | |
{ | |
@Override public State next(Transition transition) | |
{ | |
return (transition == RESUME) ? RUNNING : ILLEGAL; | |
} | |
}, | |
DEAD | |
{ | |
@Override public State next(Transition transition) | |
{ | |
return ILLEGAL; | |
} | |
}, | |
ILLEGAL | |
{ | |
@Override public State next(Transition transition) | |
{ | |
return ILLEGAL; | |
} | |
}; | |
public State next(Transition transition) | |
{ | |
return null; | |
} | |
} | |
public static enum Transition | |
{ | |
CREATE, | |
WAIT, | |
RESUME, | |
FINISH | |
} | |
public static void main(String[] args) | |
{ | |
State finish = run(State.NEW, CREATE, WAIT, RESUME, WAIT, RESUME, FINISH); | |
} | |
public static State run(State start, Transition... transitions) | |
{ | |
State state = start; | |
LOGGER.log(Level.INFO, "start state: {0}", start); | |
for (Transition transition : transitions) | |
{ | |
state = state.next(transition); | |
LOGGER.log(Level.INFO, "current state: {0}", state); | |
} | |
LOGGER.info("finished"); | |
return state; | |
} | |
} |
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