MyList.java

/**
 * @author Pakkapon Phongthawee (07580028) 
 * @license GPLv3
 */
public class MyList<Type> {
    private class Node{
        public Type data;
        public Node prev,next;
        Node(Type d){
            data = d;
        }
    }
    private Node front,rear;
    private int length;
    MyList(){
    }
    /**
     * append data to list
     * @param data
     * @return MyListObject
     */
    public MyList unshift(Type data)
    {
        length++;
        Node node = new Node(data);
        try{
            front.prev = node;
            node.next = front;
        }catch(NullPointerException e){
            rear = node;
        }
        front = node;
        return this;
    }
    /**
     * get data from front of list
     * @return dataAtFrontOfList
     */
    public Type shift()
    {
        Type output;
        try{
           output = front.data;
        }catch(NullPointerException e){
            return null;
        }
        length--;
        try{
            front = front.next;
            front.prev = null;
        }catch(NullPointerException e){
            rear = null;
        }
        return null;
    }
    /**
     * append data to list 
     * @param data
     * @return MyListObject
     */
    public MyList push(Type data){
        length++;
        Node node = new Node(data);
        try{
            rear.next = node;
            node.prev = rear;
        }catch(NullPointerException e){
            front = node;
        }
        rear = node;
        return this;
    }
    /**
     * get data from rear of list
     * @return dataAtFrontOfList
     */
    public Type pop(){
        Type output;
        try{
            output  = rear.data;
        }catch(NullPointerException e){
            return null;
        }
        length--;
        try{
            rear = rear.prev;
            rear.next = null;
        }catch(NullPointerException e){
            front = null;
        }
        return output;
    }
    /**
     * get data at specify position of list
     * Note: first data start at 0
     * @param position
     * @return 
     */
    public Type at(int position)
    {
        if(position < 0){
            throw new IndexOutOfBoundsException();
        }
        Node traveller = front;
        int i = 0;
        try{
            while(i<position){
                traveller = traveller.next;
            }
        }catch(NullPointerException e){
            throw new IndexOutOfBoundsException();
        }
        return traveller.data;
    }
    /**
     * get data at front of list
     * @return data
     */
    public Type front()
    {
        return front.data;
    }
    /**
     * get data at rear of list
     * @return data
     */
    public Type rear()
    {
        return rear.data;
    }
    /**
    * Get List length
    * @return ListLength
    **/
    public int size()
    {
        return length;
    }
    /**
     * convert MyList to Java ordinary array
     * @return ArrayOfMyList
     */
    public Object[] toArray()
    {
        Object[] arrays = new Object[length];
        int i = 0;
        Node traveller = front;
        while(traveller != null){
            arrays[i++] = traveller.data;
            traveller = traveller.next;
        }
        return arrays;
    }
}