Question

c.

You are given the following Java files:

• SLL.java that implements generic Singly Linked List, with class SLLNode listed as inner class.
• TestIntegerSLL.java that tests the SLL class by using a linked list of Integer.

In SLL class add the following method:                                                                   

1. public void moveToEnd (int i)

It will move the element at the i -th position to the end of the list.

You can assume i to be within the list, and that the first element has the position 0.

Suppose the list contains: 1,3,6,7,8,9

When calling the method with (2) as passed prameter, the return value will be 1,3,7,8,9,6

           ------------------------------------------------------------------------------------------------------------------

2. Update the main method inside TestIntegerSLL class, to have additional options to test your methods above similar to the following:                                  

.....other options..

3. Move element in given index to the end of List.

4. Quit

----------------------------------------

This file SLL.java:

public class SLL<T> {

protected SLLNode<T> head, tail;

public SLL() {
head = tail = null;
}

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

public void addToHead(T el) {
if (!isEmpty()) {
head = new SLLNode<T>(el, head);
} else {
head = tail = new SLLNode<T>(el);
}
}

public void addToTail(T el) {
if (!isEmpty()) {
tail.next = new SLLNode<T>(el);
tail = tail.next;
} else {
head = tail = new SLLNode<T>(el);
}
}

public T deleteFromHead() { // delete the head and return its info;
if (isEmpty()) {
return null;
}
T el = head.info;
if (head == tail) // if only one node on the list;
{
head = tail = null;
} else {
head = head.next;
}
return el;
}

public T deleteFromTail() { // delete the tail and return its info;
if (isEmpty()) {
return null;
}
T el = tail.info;
if (head == tail) // if only one node in the list;
{
head = tail = null;
} else { // if more than one node in the list,
SLLNode<T> tmp; // find the predecessor of tail;
for (tmp = head; tmp.next != tail; tmp = tmp.next);
tail = tmp; // the predecessor of tail becomes tail;
tail.next = null;
}
return el;
}

public T delete(T el) {
if (isEmpty()) {
return null;
} else if (head.info.equals(el)) {
return deleteFromHead();
} else if (tail.info.equals(el)) {
return deleteFromTail();
} else {
SLLNode<T> pred, tmp;// and el is in a nonhead node;
for (pred = head, tmp = head.next;
tmp != null && !tmp.info.equals(el);
pred = pred.next, tmp = tmp.next);
if (tmp != null) {
pred.next = tmp.next;
return tmp.info;
} else {
return null;
}
}
}

public void printAll() {
for (SLLNode<T> tmp = head; tmp != null; tmp = tmp.next) {
System.out.print(tmp.info + " ");
}
}

public T find(T el) {
SLLNode<T> tmp;
for (tmp = head; tmp != null && !tmp.info.equals(el); tmp = tmp.next);
if (tmp != null) // if found
{
return tmp.info;
} else {
return null;
}
}

//This is an inner class impleming the SLLNode
public class SLLNode<T> {

public T info;
public SLLNode<T> next;

public SLLNode() {
this(null, null);
}

public SLLNode(T el) {
this(el, null);
}

public SLLNode(T el, SLLNode<T> ptr) {
info = el;
next = ptr;
}
}
}

Answer 1

Code

public class SLL<T>
{
   protected SLLNode<T> head, tail;

   public SLL()
   {
       head = tail = null;
   }

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

   public void addToHead(T el)
   {
       if (!isEmpty()) {
           head = new SLLNode<T>(el, head);
       } else {
           head = tail = new SLLNode<T>(el);
       }
   }

   public void addToTail(T el) {
       if (!isEmpty()) {
           tail.next = new SLLNode<T>(el);
           tail = tail.next;
       } else {
           head = tail = new SLLNode<T>(el);
       }
   }

   public T deleteFromHead() { // delete the head and return its info;
       if (isEmpty()) {
           return null;
       }
       T el = head.info;
       if (head == tail) // if only one node on the list;
       {
           head = tail = null;
       } else {
           head = head.next;
       }
       return el;
   }

   public T deleteFromTail() { // delete the tail and return its info;
       if (isEmpty()) {
           return null;
       }
       T el = tail.info;
       if (head == tail) // if only one node in the list;
       {
           head = tail = null;
       } else { // if more than one node in the list,
           SLLNode<T> tmp; // find the predecessor of tail;
           for (tmp = head; tmp.next != tail; tmp = tmp.next);
               tail = tmp; // the predecessor of tail becomes tail;
           tail.next = null;
       }
       return el;
   }

   public T delete(T el)
   {
       if (isEmpty()) {
           return null;
       } else if (head.info.equals(el)) {
           return deleteFromHead();
       } else if (tail.info.equals(el)) {
           return deleteFromTail();
       } else {
           SLLNode<T> pred, tmp;// and el is in a nonhead node;
           for (pred = head, tmp = head.next;tmp != null && !tmp.info.equals(el);
               pred = pred.next, tmp = tmp.next);
           if (tmp != null) {
               pred.next = tmp.next;
               return tmp.info;
           } else {
               return null;
           }
       }
   }

   public void printAll()
   {
       for (SLLNode<T> tmp = head; tmp != null; tmp = tmp.next) {
           System.out.print(tmp.info + " ");
       }
   }

   public T find(T el)
   {
       SLLNode<T> tmp;
           for (tmp = head; tmp != null && !tmp.info.equals(el); tmp = tmp.next);
           if (tmp != null) // if found
           {
                   return tmp.info;
           } else {
               return null;
           }
       }

   //This is an inner class impleming the SLLNode
   public class SLLNode<T> {
       public T info;
       public SLLNode<T> next;

       public SLLNode() {
           this(null, null);
       }

       public SLLNode(T el) {
           this(el, null);
       }

       public SLLNode(T el, SLLNode<T> ptr) {
           info = el;
           next = ptr;
       }
   }
   public void moveToEnd (int i)
   {
       T info=null;
       int j=0;
       for (SLLNode<T> tmp = head ; j<=i; tmp = tmp.next,j++) {
           info=tmp.info;
       }
       this.delete(info);
       this.addToTail(info);
   }
}

As you not provided he code for TestIntegerSLL.java so for testing purpose i have made a code

TestIntegerSLL.java

public class TestIntegerSLL {

   public static void main(String[] args) {
      
       SLL<Integer> list=new SLL<>();
       list.addToHead(1);
       list.addToTail(3);
       list.addToTail(6);
       list.addToTail(7);
       list.addToTail(8);
       list.addToTail(9);
       list.printAll();
       System.out.println("\nAfter moving element at index 2 to end");
      
       list.moveToEnd(2);
       list.printAll();
   }

}

output

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