Notes

package csdappliccation;
import java.util.*;
public class EXF4_38
{
public static Scanner input = new Scanner(System.in);
public static char again,head,tail;
public static void main(String[] args)
{
SLL<Character> sl = new SLL<Character>();
char choice,word,refer;
int num;
for(;;)
{
System.out.printf("Main menunA. Add NodenB. TracenC. MakeNull nD. ExitnChoose: ");
choice= input.next().charAt(0);
if((choice=='A')||(choice=='a'))
{
do
{
System.out.printf("Enter Character to add: ");
word=input.next().charAt(0);
sl.AddTail(word);
System.out.print("Again? ");
again= input.next().charAt(0);
}while((again=='y')||(again=='Y'));
continue;
}
else if((choice=='b')||(choice=='B'))
{
sl.Trace();
System.out.printf("nBack to Main: ");
again= input.next().charAt(0);
if ((again=='y')||(again=='Y'))
{
continue;
}
else
{
break;
}
}
else if((choice=='c')||(choice=='C'))
{
System.out.print("Are you sure?");
again= input.next().charAt(0);
if ((again=='y')||(again=='Y'))
{
sl = new SLL<Character>();
}
System.out.print("Back to Main: ");
again= input.next().charAt(0);
if ((again=='y')||(again=='Y'))
{
continue;
}
else
{
break;
}
}
else if((choice=='d')||(choice=='D'))
{
System.out.print("GoodBye!!!");
break;
}
else
{
System.out.printf("nWrong Input!!!");
continue;
}
}
}
public static class SLLNode<T>
{
public T info;
public SLLNode<T> next;
public SLLNode()
{
next = null;
}
public SLLNode(T el)
{
info = el;
next = null;
}
public SLLNode(T el, SLLNode<T> ptr)
{
info = el;
next = ptr;
}
}
public static class SLL<T>
{
private SLLNode<T> head, tail;
public SLL()
{
head = tail = null;
}
public boolean isEmpty()
{
return head == null;
}
public void AddHead(T el) {
head = new SLLNode<T>(el,head);
if (tail == null)
tail = head; // only node of list
}
public void AddTail(T el)
{
if (isEmpty())
head = tail = new SLLNode<T>(el);
else
{
tail.next = new SLLNode<T>(el);
tail = tail.next;
tail.next = head;
}
}
public T RemoveHead()
{
if (isEmpty())
return null;
T el = head.info;
if (head == tail)
head = tail = null;
else
head = head.next;
tail.next=head;
return el;
}
public T RemoveTail()
{
if (isEmpty())
return null;
T el = tail.info;
if (head == tail) // only one node
head = tail = null;
else
{
SLLNode<T> p; // find predecessor of tail
for (p = head; p.next != tail; p = p.next);
tail = p; // predecessor of tail is the new tail
tail.next = head;

}
return el;
}
public String Print()
{
SLLNode<T> p; String s = "";
for (p = head; p != null; p = p.next)
s=s+p.info.toString() + " ";
return s;
}
public SLLNode<T> GetNode(T el)
{
SLLNode<T> p = head;
while (p != null && p.info != el) p = p.next;
return p;
}
public void InsertAfter(T el, SLLNode<T> ptr )
{
if (ptr != null)
if (tail == ptr) AddTail(el);
else ptr.next = new SLLNode<T>(el, ptr.next);
}
public void InsertBefore(T el, SLLNode<T> ptr )
{
if (ptr != null)
if (head == ptr) AddHead(el);
else
{
SLLNode<T> pred, t; // find el’s predecessor
for (pred = head, t = head.next;
t != null && t.info != ptr.info;
pred = pred.next, t = t.next) ;
InsertAfter(el,pred);
}
}
public T delete(T el)
{ // delete node with element el
if (isEmpty()) return null;
if (el == head.info) return RemoveHead();
if (el == tail.info) return RemoveTail();
SLLNode<T> pred, t; // find el’s predecessor
for (pred = head, t = head.next;
t != null && t.info != el;
pred = pred.next, t = t.next) ;
if (t == null) return null; // if el was not found
else {
pred.next = t.next;
return el; }
}
public void Trace()
{
SLLNode<T> p = head;
if(isEmpty())
{
System.out.printf("List is Emptyn");
}
else
{
do
{
System.out.print(delete(p.info)+" ");
p=p.next.next.next.next;
}while(p.next!=p);
}
}
}
}