With respect to space, it's better to use a singly-linked list because it has half the overhead of a doubly-linked list. With respect to time, it's better to use a double-linked list because insertions and deletions can occur at either end of the deque, and a singly-linked list requires a full traversal of the deque for a deletion at the down-stream end.
void f(Stack<?> s) { ... }
and
void f(Stack<Object> s) { ... }
The first declaration is a generic method, capable of accepting a stack of any type as a parameter value. The second declaration is a non-generic method that can accept only a stack of ojects as a parameter value.
1 2 3 4 and writes the numbers 4 3 2 1. Is it
possible to write a program that reads 1 2 3 4 and writes (1 4 2 3)? If
so, show the program; if not, explain why no such program is possible.
It's not possible. The only place to store 2 and 3 while 4 is
being read and printed is on the stack, with 2 being pushed before 3.
Once 4 is printed, it's time to print 2, but the only number
available for printing is 3, the top of the stack.
See Laforge, table 4.10, page 159.
This page last modified on 15 October 2009.