Stack

Stack: is a subclass of Vector that implements a standard last-in, first-out stack.
Stack only defines the default constructor, which creates an empty stack. Stack includes all the methods defined by Vector, and adds several of its own.

Stack( )

Apart from the methods inherited from its parent class Vector, Stack defines following methods:

SN	Methods with Description
1	boolean empty() Tests if this stack is empty. Returns true if the stack is empty, and returns false if the stack contains elements.
2	Object peek( ) Returns the element on the top of the stack, but does not remove it.
3	Object pop( ) Returns the element on the top of the stack, removing it in the process.
4	Object push(Object element) Pushes element onto the stack. element is also returned.
5	int search(Object element) Searches for element in the stack. If found, its offset from the top of the stack is returned. Otherwise, .1 is returned.

Example:

The following program illustrates several of the methods supported by this collection:

import java.util.*; class StackDemo { static void showpush(Stack st, int a) { st.push(new Integer(a)); System.out.println("push(" + a + ")"); System.out.println("stack: " + st); } static void showpop(Stack st) { System.out.print("pop -> "); Integer a = (Integer) st.pop(); System.out.println(a); System.out.println("stack: " + st); } public static void main(String args[]) { Stack st = new Stack(); System.out.println("stack: " + st); showpush(st, 42); showpush(st, 66); showpush(st, 99); showpop(st); showpop(st); showpop(st); try { showpop(st); } catch (EmptyStackException e) { System.out.println("empty stack"); } } }

This would produce following result:

stack: [ ] push(42) stack: [42] push(66) stack: [42, 66] push(99) stack: [42, 66, 99] pop -> 99 stack: [42, 66] pop -> 66 stack: [42] pop -> 42 stack: [ ] pop -> empty stack