Returns <tt>true</tt> if this collection contains the specified element.
More formally, returns <tt>true</tt> if and only if this collection
contains at least one element <tt>e</tt> such that
<tt>(o==null ? e==null : o.equals(e))</tt>.
@param o element whose presence in this collection is to be tested
@return <tt>true</tt> if this collection contains the specified
element
@throws ClassCastException if the type of the specified element
is incompatible with this collection
(<a href="#optional-restrictions">optional</a>)
@throws NullPointerException if the specified element is null and this
collection does not permit null elements
(<a href="#optional-restrictions">optional</a>)
Returns <tt>true</tt> if this collection contains the specified element. More formally, returns <tt>true</tt> if and only if this collection contains at least one element <tt>e</tt> such that <tt>(o==null ? e==null : o.equals(e))</tt>.
@param o element whose presence in this collection is to be tested @return <tt>true</tt> if this collection contains the specified element @throws ClassCastException if the type of the specified element is incompatible with this collection (<a href="#optional-restrictions">optional</a>) @throws NullPointerException if the specified element is null and this collection does not permit null elements (<a href="#optional-restrictions">optional</a>)