Question

public class myLinkedList<E extends Comparable<E>>{
      private Node<E> head = null;             
      private Node<E> tail = null;             
  
      public myLinkedList() {
       head = null;
      }

public void concatenateList (myLinkedList<E> M) {//attach another linkedList refered by M to the end of this linkedList
      }
  
      public int searchElement (E targetElement){//test if a target element can be found on the list, return the occurrences of the target element  
      
      }
  
      public void removeElement(E targetElement){//remove all target element that can be found on the list

      }
  
      public E middleElement(){//find and return the element that stored at the middle node of a linkedList

      }

=====================================================================================

Node class

public class Node<E extends Comparable<E>> {

   private E item;            // reference to the element stored at this node
    private Node<E> next;         // reference to the subsequent node in the list
    /**
     * Creates a node with the given element and next node.
     *
     * @param e the element to be stored
     * @param n reference to a node that should follow the new node
     */
    public Node(E e, Node<E> n) {
       item = e;
      next = n;
    }
  
    public Node(E e) {
       item = e;
      next = null;
    }
    // Accessor methods
    public E getItem() { return item; }
    public Node<E> getNext() { return next; }
    // Modifier methods
    public void setNext(Node<E> n) { next = n; }
} //----------- end of nested Node class -----------

Answer 1

//attach another linkedList refered by M to the end of this linkedList

public void concatenateList (myLinkedList<E> M) {
   //To concatenate two linked list we have to make the last node of first list to point to first node of second list
   if (head == null) {
       head = tail;
       tail.setNext(head);
   } else {
       Node temp = head;
       while (temp.next != null)
           temp = temp.next;

       temp.next = tail;
       tail.setNext(temp.next);
   }
  
}

//test if a target element can be found on the list, return the occurrences of the target element
public int searchElement(E targetElement){

   int index=list.indexOf(targetElement);   
   return index;
  
}

//remove all target element that can be found on the list
public void removeElement(E targetElement){
  
   int index=list.indexOf(targetElement);
  
   if(index==0)
{
head=head.next;
}
else
{
Node n=head;
Node n1=null;
for(int i=0;i<index-1;i++)
{
n=n.next;
}
n1=n.next;
n.next=n1.next;

}

}

//find and return the element that stored at the middle node of a linkedList
public E middleElement(){
   //take two nodes pointing to the first node
   //Increment first with two nodes and second with one, at a time.
   //Loop until the p1 loop reaches the end. At this point, the p2 will be at the middle.
  
  
   Node p1=head;
   Node p2=head;
     
   while ( p2.next != null ) {
   p2 = p2.next;
   if (p2.next != null) {
   p2 = p2.next;
   p1 = p1.next;
   }
   }
   return (E) p1;
  
}