How to convert NFA/DFA to java?

Question

I have a scenario where I have designed the NFA and using JFLAP I have converted it to DFA.

I need to know, how to code it in Java?

Basically how to implement those state transitions in Java. I have seen some examples which do this using switch and if statements, but I can't see any relation to DFA/NFA design and how to use it to implement in Java.

Answer 1

if you want to use a more object oriented design over while(true)switch(state){...}

public class State{
    private Map<Character,State> transitions=new HashMap<Character,State>();

    public void addTransition(char ch,State st){
        transitions.put(ch,st);
    }

    public State next(char ch){
        return transitions.get(ch);
    }

    private boolean fin=false;
    public boolean isFinal(){return fin;}
    public boolean setFinal(boolean f){fin=f;}        


}

and then the loop will be

State currState=startState;
while(currState!=null && input.hasNextChar()){//you can also end directly when final state is reached
    char next = input.nextChar();//get next character
    currState = currState.next(next);
}

if(currState!=null && currState.isFinal()){
    // reached final state
}else{
    // to bad didn't match
}