Implementation of several common methods of LinkedList, Java

Implementation of several common methods of LinkedList

/**
 *  Implementation of several common methods of LinkedList
 *
 *  @author Jayesh Chandrapal
 *  @version 1.1
 */

import java.util.*;
import java.lang.*;

interface MyList<E> {
    public void insertFront(E data);
    public void insertRear(E data);
    public void insertAtIndex(int index, E data);
    public void delete(E data);
    public void deleteAtIndex(int index);
    public void reverse();
    public void merge(LinkedList<E> otherLinkedList);
    public void print();
    
    public boolean isPalindrome();
    public boolean hasCycle();
    public boolean hasDuplicates();
    public boolean empty();
    
    public E itemFromLast(int n);
    public E middleElement();
    
    public int size();
}

class List<E> implements MyList<E> {
    private class Node<E> {
        E data;
        Node<E> next;
        
        public Node(E data, Node<E> next) {
            this.data = data;
            this.next = next;
        }
    }
    
    int size;
    Node<E> head;
    
    public List() {
        size = 0;
        head = null;
    }
    
    public void insertFront(E data) {
        Node<E> newnode = new Node<E>(data, null);
        
        if(!empty()) {
            newnode.next = head;
        }
        
        head = newnode;
        size += 1;
    }
    
    public void insertRear(E data) {
        Node<E> newnode = new Node<E>(data, null);
        
        if(empty()) {
            head = newnode;
        } else {
            Node<E> current = head;
            while(current.next != null) {
                current = current.next;
            }
            
            current.next = newnode;
        }
        
        
        size += 1;
    }
    
    public void insertAtIndex(int index, E data) {
        if(index < 0 || index > size) {
            throw new IllegalArgumentException();
        }
        
        Node<E> newnode = new Node<E>(data, null);
        
        if(empty()) {
            head = newnode;
        } else {
            if(index == 0) {
                newnode.next = head;
                head = newnode;
            } else {
                Node<E> current = head;
                int i = 0;
                while(current != null) {
                    if(i == index - 1) {
                        newnode.next = current.next;
                        current.next = newnode;
                        break;
                    }
                    
                    current = current.next;
                    i += 1;
                }
            }
        }
        
        size += 1;
    }
    
    public void delete(E data) {}
    public void deleteAtIndex(int index) {}
    public void reverse() {}
    public void merge(LinkedList<E> otherLinkedList) {}
    
    public boolean isPalindrome() {
        return false;
    }
    
    public boolean hasCycle() {
        return false;
    }
    
    public boolean hasDuplicates() {
        return false;
    }
    
    public boolean empty() {
        return size == 0 && head == null;
    }
    
    public E itemFromLast(int n) {
        if(empty() || n <= 0) {
            throw new IllegalArgumentException();
        }
        
        Node<E> first = head;
        Node<E> second = head;
        for(int i = 0; i < n - 1; i++) {
            first = first.next;
        }
        
        if(first == null) {
            return null;
        }
        
        while(first.next != null && second.next != null) {
            first = first.next;
            second = second.next;
        }
        
        if(second != null) {
            return second.data;
        } else {
            return null;
        }
    }
    
    public E middleElement() {
        return null;
    }
    
    public int size() {
        return size;
    }
    
    public void print() {
        Node<E> current = head;
        while(current != null) {
            System.out.print("[ " + current.data + " ] ");
            current = current.next;
        }
        System.out.println();
    }
}

class Rextester
{  
    public static void main(String args[])
    {
        MyList<Integer> items = new List<Integer>();
        
        items.insertFront(10);
        items.insertFront(20);
        items.insertFront(30);
        
        items.insertRear(5);
        items.insertRear(2);
        
        items.insertAtIndex(2, 3);
        
        System.out.println("Size = " + items.size());
        items.print();
        System.out.println(items.itemFromLast(1));
        
        System.out.println("OK");
    }
}


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