ListTwo.java

public class ListTwo<T> implements IList<T> {
	ElemTwo<T> first;
	ElemTwo<T> last;
	@Override
	public void addFirst(T newData) {
		ElemTwo niu = new ElemTwo(newData, this.first, null);
		this.first = niu;
		if(this.last == null){
			this.last = niu;
		}
	}
	@Override
	public void addLast(T newData) {
		if(this.first == null){
			this.addFirst(newData);
			return;
		}
		ElemTwo<T> cur = this.first;
		while(cur.getNext() !=null){
			cur = cur.getNext();
		}
		ElemTwo niu = new ElemTwo(newData, cur, null);
		cur.setNext(niu);
	}
	@Override
	public void addAtPosition(T newData, int position) throws ListException {
		if(position == 0){
			this.addFirst(newData);
			return;
		} else if(this.size() == position){
			this.addLast(newData);
			return;
		}
		ElemTwo<T> cur = this.first;
		while(cur.getNext() !=null){
			cur = cur.getNext();
			if(cur.getData().equals(newData)){
				ElemTwo<T> niu = new ElemTwo(newData, cur.getPrev(), cur.getNext());
				cur.getNext().setPrev(niu);
				cur.getPrev().setNext(niu);
			}
		}
		throw new ListException("Out of list");
	}
	@Override
	public int size() {
		if(this.first==null){
			return 0;
		}
		int pos = 1;
		ElemTwo<T> cur = this.first;
		while(cur.getNext() !=null){
			cur = cur.getNext();
			pos+=1;
		}
		return pos;
	}
	@Override
	public T removeFirst() throws ListException {
		if(this.first == null) throw new ListException("List are empty!");
		T data = this.first.getData();
		this.first = this.first.getNext();
		return data;
	}
	@Override
	public T removeLast() throws ListException {
		if(this.first == null){
			throw new ListException("Empty list");
		};
		if(this.first.getNext() == null){
			return this.removeFirst();
		}
		ElemTwo<T> cur = this.first;
		while(cur.getNext() !=null){
			cur = cur.getNext();
		}
		if(this.first.getNext() == cur){
			this.first = null;
		}
		cur.setNext(null);
		return cur.getData();
	}
	@Override
	public T remove(int position) throws ListException {
		if(position == 0){
			return this.removeFirst();
		}else if(this.size() == position){
			return this.removeLast();
		}
		int pos = 0;
		ElemTwo<T> cur = this.first;
		while(cur.getNext() !=null){
			if(pos == position){
				cur.getNext().setPrev(cur.getNext());
				cur.getPrev().setNext(cur.getPrev());
				return cur.getData();
			}
			cur = cur.getNext();
			pos++;
		}
		
		throw new ListException("Out of list");
	}
	@Override
	public int find(T dataToFind) {
		ElemTwo<T> cur = this.first;
		int pos = 0;
		while(cur!=null){
			if(cur.getData().equals(dataToFind)){
				return pos;
			}			
			cur = cur.getNext();
			pos++;
		}
		throw new IllegalStateException("Not found");
	}
	@Override
	public boolean contains(T data) {
		try{
			this.find(data);
		}catch(IllegalStateException e){
			return false;
		}
		return true;
	}
	@Override
	public void print() {
		ElemTwo<T> cur = this.first;
		while(cur !=null){
			System.out.print("[" + cur.getData() + "]");
			cur = cur.getNext();
		}
		return;
	}
	public static void main(String[] args) {
		try {
			ListTwo<Integer> list = new ListTwo<>();
			assert(list.size() == 0);
			list.addFirst(25);
			assert(list.size() == 1);
			list.addFirst(10);
			assert(list.size() == 2);
			list.addLast(100);
			assert(list.size() == 3);
			list.removeFirst();
			assert(list.size() == 2);
			list.removeLast();
			assert(list.size() == 1);
			assert(list.contains(100) == false);
			assert(list.contains(25) == true);
			list.addLast(77);
			list.addLast(33);
			assert(list.find(25) == 0);
			assert(list.find(77) == 1);
			assert(list.find(33) == 2);
			list.remove(0);
			assert(list.find(77) == 0);
			list.print();
		} catch (ListException e) {
		}
	}
	public void join(IList<T> list) {
		while(list.size()!=0){
			try {
				this.addLast(this.removeLast());
			} catch (ListException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}		
	}
}