状态

public interface state {
    public void doaction(context context);
}

public class startstate implements state {
    private context context;
    public startstate(){}
    @override
    public void doaction(context context){
        this.context = context;
        this.context.setstate(this);
        system.out.println("player is in startstate");
    }

    public string tostring(){
        return "start state";
    }
}

public class endstate implements state {
    private context context;
    public endstate(){}
    @override
    public void doaction(context context){
        this.context = context;
        this.context.setstate(this);
        system.out.println("player is in endstate");
    }

    public string tostring(){
        return "end state";
    } 
}

public class main {
    public static void main(string args[]){
        context context = new context();
        state state = new startstate();
        state.doaction(context);
        //current state
        system.out.println(context.getstate().tostring());

        state state2 = new endstate();
        state2.doaction(context);
        //new state
        system.out.println(context.getstate().tostring());
    }
}

Player is in StartState
Start State
Player is in EndState
End State