java - 为什么 Set 被编译器标记为 "not a known variable in this context"？

Question

这是我的代码；

import java.util.*;  

  class State extends HashMap<Character, State>{

    boolean isFinal;

    State () {
        isFinal = false;
        }

    }

      class Automaton{
        private Set<State> allStates;
        private Set<State> finalStates;
        private State initialState;
        private State currentState;
        private Set<Character> alphabet;


        Automaton() {


            allStates = new Set<State>();
        }

 }

Answer 1

allStates = new Set<State>();

Set 是一个接口(interface)。那么也许您指的是 HashSet？