복습 의 데이터 구조

package link;

public class FirstLastLinkList {
	private Node first; //   
	private Node last; //   
	
	
	/**
	 *           
	 */
	public void insertFirstNode(long value){
		Node node = new Node(value);
		if(isEmpty()){
			last = node;
		}
		node.next = first;
		first = node;
	}
	
	/**
	 *           
	 */
	public void insertLastNode(long value){
		Node node = new Node(value);
		if(isEmpty()){
			first = node;
		}else{
			last.next = node;
		}
		last = node;
	}
	
	/**
	 *     
	 */
	public void display(){
		Node current = first;
		while(current != null){
			current.display();
			current = current.next;
		}
		System.out.println();
	}
	
	/**
	 *       
	 */
	public void deleteFirst(){
		if(first == null) return;
		Node tmp = first;
		if(first.next == null){
			last = null;
		}
		first = tmp.next;
	}
	
	/**
	 *     
	 */
	public Node find(long value){
		Node current = first;
		while(current.data != value){
			if(current.next == null){
				return null;
			}
			current = current.next;
		}
		return current;
	}
	
	/**
	 *        
	 */
	public void delete(long value){
		Node current = first;
		Node tmp = first;
		while(current.data != value){
			if(current.next == null){
				return;
			}
			tmp = current;
			current = current.next;
		}
		if(current == first){
			first = current.next;
		}else{
			tmp.next = current.next;
		}
	}
	
	public boolean isEmpty(){
		return (first == null);
	}
}