Associates the specified value with the specified key in this map
(optional operation). If the map previously contained a mapping for
the key, the old value is replaced by the specified value. (A map
<tt>m</tt> is said to contain a mapping for a key <tt>k</tt> if and only
if {@link #containsKey(Object) m.containsKey(k)} would return
<tt>true</tt>.)
@param key key with which the specified value is to be associated
@param value value to be associated with the specified key
@return the previous value associated with <tt>key</tt>, or
<tt>null</tt> if there was no mapping for <tt>key</tt>.
(A <tt>null</tt> return can also indicate that the map
previously associated <tt>null</tt> with <tt>key</tt>,
if the implementation supports <tt>null</tt> values.)
@throws UnsupportedOperationException if the <tt>put</tt> operation
is not supported by this map
@throws ClassCastException if the class of the specified key or value
prevents it from being stored in this map
@throws NullPointerException if the specified key or value is null
and this map does not permit null keys or values
@throws IllegalArgumentException if some property of the specified key
or value prevents it from being stored in this map
Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A map <tt>m</tt> is said to contain a mapping for a key <tt>k</tt> if and only if {@link #containsKey(Object) m.containsKey(k)} would return <tt>true</tt>.)
@param key key with which the specified value is to be associated @param value value to be associated with the specified key @return the previous value associated with <tt>key</tt>, or <tt>null</tt> if there was no mapping for <tt>key</tt>. (A <tt>null</tt> return can also indicate that the map previously associated <tt>null</tt> with <tt>key</tt>, if the implementation supports <tt>null</tt> values.) @throws UnsupportedOperationException if the <tt>put</tt> operation is not supported by this map @throws ClassCastException if the class of the specified key or value prevents it from being stored in this map @throws NullPointerException if the specified key or value is null and this map does not permit null keys or values @throws IllegalArgumentException if some property of the specified key or value prevents it from being stored in this map