Thread: STACK USING LINKED LIST------------HELP !

hello i m jayesh.,.....can somebody help me with this......


import java.io.*;

class StackNode
{
Object info;
StackNode next=null;
StackNode prev=null;
StackNode(Object el)
{
info=el;
}
}

class Stack
{
StackNode head,tail;
Stack(){}

boolean isEmpty()
{ return head==null;}

void push(Object el)
{
if(isEmpty())
head=tail=new StackNode(el);
else
{
tail.next=new StackNode(el);
tail.prev=tail;
tail=tail.next;
}
}

Object pop()
{
Object el;
el=tail.info;
tail=tail.prev;
return el;
}

Object peek()
{ return tail.info;}
}

class StackUsingLinkedList
{
public static void main(String args[])throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int x,in;

Stack s=new Stack();

System.out.println("STACK IMPLEMENTATION USING INT ARRAY");

do
{
System.out.println("\n\nENTER CHOICE\n1.PUSH 2.POP 3.PEEK 4.EXIT");
x=Integer.parseInt(br.readLine());

switch(x)
{
case 1:
System.out.println("Enter an integer");
in=Integer.parseInt(br.readLine());
s.push(in);
break;

case 2:
if(!s.isEmpty())
System.out.println("Element at the top of the stack : "+s.pop());
else
System.out.println("Stack is Empty");
break;

case 3:
if(!s.isEmpty())
System.out.println("Element at the top of the stack : "+s.peek());
else
System.out.println("Stack is Empty");
break;

case 4:
break;
}
}
while(x!=4);
}
}