Returns the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element. More formally, returns the lowest index <tt>i</tt> such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.
element, or -1 if this list does not contain this element.
More formally, returns the lowest index <tt>i</tt> such that
(o==null ? get(i)==null : o.equals(get(i))),
or -1 if there is no such index.