Well, If you have a eclipse IDE [Open source www.eclipse.org] just put a break point and you will be able to trace the code. Or better would be to take a pen and paper and note down the values of x and z after each iteration.
Also ordinal() public final int ordinal() Returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero). Most programmers will have no use for this method. It is designed for use by sophisticated enum-based data structures, such as EnumSet and EnumMap.