how to access the key in a map java code example

Example 1: java map get the key from value

public static <T, E> Set<T> getKeyByValue(Map<T, E> map, E value) {
    return map.entrySet()
              .stream()
              .filter(entry -> Objects.equals(entry.getValue(), value))
              .map(Map.Entry::getKey)
              .collect(Collectors.toSet());
}

Example 2: access each key and value in a hashmap java

// access each key and corresponding value in a hashmap
HashMap<Integer, Integer> map = new HashMap<>();

for(Map.Entry<Integer, Integer> entry : map.entrySet()){
  entry.getKey();
  entry.getValue();
}