Remove all entries except the given keys

removeAllExcept.java

/** Remove all entries except the given keys */
private <K,V>void removeAllExcept(Map<K,V> map, K... keys) {
  Map<K,V> objs = new HashMap<K,V>(keys.length);
  for (K key : keys)
    objs.put(key, map.get(key));
  map.clear();
  map.putAll(objs);
}

/** Remove all entries except the given keys */
private <K,V>void removeAllExcept(Map<K,V> map, Collection<K> keys) {
  Map<K,V> objs = new HashMap<K,V>(keys.size());
  for (K key : keys)
    objs.put(key, map.get(key));
  map.clear();
  map.putAll(objs);
}