Constructs a new set containing the elements in the specified
collection. The <tt>HashMap</tt> is created with default load factor
(0.75) and an initial capacity sufficient to contain the elements in
the specified collection.
@param c the collection whose elements are to be placed into this set
@throws NullPointerException if the specified collection is null
Constructs a new set containing the elements in the specified collection. The <tt>HashMap</tt> is created with default load factor (0.75) and an initial capacity sufficient to contain the elements in the specified collection.
@param c the collection whose elements are to be placed into this set @throws NullPointerException if the specified collection is null