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

Parameters:

o

element to search for

Returns:  the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element

Exceptions:

ClassCastException		if the type of the specified element is incompatible with this list (optional)
NullPointerException		if the specified element is null and this list does not permit null elements (optional)