the code simply means that you are creating a single double-dimension array, having 2 rows, with one element each(and not 2 different arrays). Think of a 2 dimensional array(in this case) as a 2*1 matrix.
Thanks. You can refer to the core SCJP concepts in more coarse level at: SCJP Coarse Concepts [ May 05, 2008: Message edited by: Devesh Chanchlani ]
(a) please use code tags, multi-nested loops are impossible to read (and understand) if not formatted.
(b) Why are you doing the for loop with j4? In that loop, you are actually counting up to the value in the array, not to the array's length. Your array has 3 dimension, so 3 nested loops should do for printing out all the elements.