A-star model in java

Model.java

import java.util.PriorityQueue;
import java.util.ArrayList;

class Model{
    
    private class State implements Comparable<State>{
        int value;
        int pathCost;
        @Override
        public int compareTo(State state){
            if(value<state.value){
                return -1;
            }else if(value>state.value){
                return 1;
            }else{
            	return 0;
            }
        }
    }
    
    private class Action{
        State state;
        State successor;
        int cost;
    }
    
    PriorityQueue<State> mQueue = new PriorityQueue<>();
    
    void start(){
        State initialState = new State();
        initialState.pathCost = 0;
        initialState.value = getHeu(initialState);
        mQueue.offer(initialState);
        while(!mQueue.isEmpty()){
            State state = mQueue.poll();
            if(isGoal(state)){
                //결과를 어떻게 할까요?
                break;
            }else{
                ArrayList<Action> actions = getActions(state);
                for(Action action : actions){
                    State successor = getSuccessor(state,action);
                    mQueue.offer(successor);
                }
            }
        }
    }
    
    private ArrayList<Action> getActions(State state){
        ArrayList<Action> actions = new ArrayList<>();
        /*state에서 할수있는 action들을 추가하세요
        Action action = new Action();
        action.cost = ?;
        action.successor = ?;
        actions.add(action);
        */
        return actions;
    }
    
    private State getSuccessor(State state, Action action){
        State successor = new State();
        successor.pathCost = state.pathCost + action.cost;
        successor.value = getValue(successor);
        return successor;
    }
    
    private int getValue(State state){
        return state.pathCost + getHeu(state);
    }
    
    private int getHeu(State state){
        int heu=0;
        //휴리스틱을 정의하세요
        return heu;
    }
    
    private boolean isGoal(State state){
        return state.value == state.pathCost;
    }
}