如何从 Hashmap 中获取值<String, Object> ?

Question

I need a Map that can have values of any type. So I've tried to use HashMap . However, if I try to get a value from the map, the IDE says that the type doesn't match.

This is a part of my code with the matter:

Map<String, Object> state1 = new HashMap<>();
state1.put("location", exit1);
state1.put("direction", direction);
state1.put("number", 0);
Deque<Map> q = new ArrayDeque<>();
q.add(state1);
List<Integer> numbers = new ArrayList<>();

while (!q.isEmpty()) {
    Map<String, Object> state = q.poll();
    Pair location = state.get("location");

The variables exit1 , direction are already defined before this part, so you may ignore about that. Also, you don't have to care about the code below this part.

My IDE says that the line Map<String, Object> state = q.poll(); has incompatible types — Pair is required but Object is found. How can I make this compatible?

I am working on a problem that can run only one file, so I can't implement a new class.

Answer 1

...
Pair location = null;
if(state.get("location") instanceof Pair){
  Pair location = (Pair)state.get("location");
}
else{
...
}

Answer 2

您可以像这样指定泛型类型：

Deque<Map<String, Object>> q = new ArrayDeque<>();