public static String join(final long[] array, final char separator) {
        if (array == null) {
            return null;
        }
        return join(array, separator, 0, array.length);
    }
public static String join ( final long [ ] array , final char separator ) { if ( array == null ) { return null ; } return join ( array , separator , 0 , array . length ) ; }
<p>
Joins the elements of the provided array into a single String containing the provided list of elements.
</p>

<p>
No delimiter is added before or after the list. Null objects or empty strings within the array are represented
by empty strings.
</p>

<pre>
StringUtils.join(null, *)               = null
StringUtils.join([], *)                 = ""
StringUtils.join([null], *)             = ""
StringUtils.join([1, 2, 3], ';')  = "1;2;3"
StringUtils.join([1, 2, 3], null) = "123"
</pre>

@param array
the array of values to join together, may be null
@param separator
the separator character to use
@return the joined String, {@code null} if null array input
@since 3.2