get key from map in 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: java get keys from hashmap
//returns as set
hashmap.keySet()