Object element = elements[top--];
elements[top+1] = null;
public static void main(String args)
Stack stack = new Stack(2);
Listing2-49 describesacollectionknownasa stack ,adatastructurethatstoresele-
ments in last-in, first-out order. Stacks are useful for remembering things, such as the
instruction to return to when a method stops executing and must return to its caller.
Stack providesa push() methodforpushingarbitraryobjectsontothe top ofthe
stack,anda pop() methodforpoppingobjectsoffthestack'stopinthereverseorder
to which they were pushed.
After creating a Stack object that can store a maximum of two objects, main()
invokes push() three times, to push three String objects onto the stack. Because
thestack'sinternalarraycanstoretwoobjectsonly, push() outputsanerrormessage
when main() tries to push "C" .
At this point, main() attempts to pop three Object s off of the stack, outputting
each object to the standard output device. The first two pop() method calls succeed,
when it is called.
When you run this application, it generates the following output:
stack is full