HashMap number mapping

HashMap.md

From number of mapping

Java 19 add newHashMap(int) to HashMap and LinkedHashMap.

See: Java doc HashMap

Calculate capacity from load factory

private static final short DEFAULT_LOAD_FACTOR = .75;

public static int calculateMapCapacity(int numMappings) {
  return (int) Math.ceil(numMappings / (double) DEFAULT_LOAD_FACTOR);
}

public static <K, V> HashMap<K, V> newHashMap(final int numMappings) {
  return new HashMap<>(calculateMapCapacity(numMappings), DEFAULT_LOAD_FACTOR);
}