Abstract Generic Class defining the LinkedList ADT interface.

LikedList.java

package it.pm.algorithms;

/**
 * Abstract class defining a linked list interface.
 *
 * @param <T>
 *      Type to use for Nodes' values
 *
 * @author Paolo Maresca <plo.maresca@gmail.com>
 */
public abstract class LinkedList<T extends Comparable<T>>
{
    protected Node head;
    protected StringBuilder serialized;

    public abstract void iterativeReverse();
    public abstract void recursiveReverse();

    public abstract void insert(T value);
    public abstract Node search(T value);
    public abstract Node delete(T value);
    public abstract T min();
    public abstract T max();


    public LinkedList() { serialized = new StringBuilder(); }

    public String printRecursive()
    {
        serialized.delete(0, serialized.toString().length());
        if(head == null)
            return serialized.toString();
        else
            return _print(head);
    }

    private String _print(Node elem)
    {
        serialized.append(elem.value);
        serialized.append(" ");

        if(elem.next == null)
            return serialized.toString();
        else
            return _print(elem.next);
    }

    public String printIterative()
    {
        serialized.delete(0, serialized.toString().length());
        if(head == null)
            return serialized.toString();

        Node successor = head;
        do {
            serialized.append(successor.value);
            serialized.append(" ");
        } while((successor = successor.next) != null);

        return serialized.toString();
    }

    public static class Node<T>
    {
        public T value;
        public Node next;

        public Node(T value) { this.value = value; }
    }

}