java實現雙向鏈表的操作

單向鏈表只能單方向的查找鏈表中的節點，並且在插入或者刪除某一個節點的時候，必須知道其的前一個節點。當單向鏈表的前一個節點指向這個鏈表的第一個節點的時候稱爲循環鏈表。

雙向鏈表的每個結構分爲三個部分，一個左指針 llink , 一個數據data ,一個右指針 rlink,其手llink存放當前節點的前一個節點，rlink指向當前節點的後一個節點。因此構造java節點類型如下

public class NodeType {
	public NodeType llink;
	public int data;
	public NodeType rlink;
	
	
	public NodeType(int data){
		this.data = data;
	}
	
	public NodeType(){
	}
	
}

下面是對雙向鏈表的相關操作

public class doubleLinkedListTest {

	/**
	 * 獲取給定head所指向鏈表的長度
	 * @param head
	 */
	public static void getAllNodes(NodeType head){
		NodeType current = head.rlink;
		while(current != head){
			System.out.println("前一個節點是: " + current.llink .data + "   當前節點是:"+ current.data + "  後一個節點是:"
					+current.rlink.data);
			current = current.rlink;
		}
	}

	
	/**
	 * 
	 * @param head
	 * @param newNode 需要插入的新節點
	 */
	public static void insert(NodeType head,NodeType newNode){
		NodeType current = head.rlink;
		NodeType prev = null;
		while(current != head && current.data < newNode.data){
			prev = current;
			current = current.rlink;
		}
		
		prev.rlink = newNode;
		newNode.llink = prev;
		newNode.rlink = current;
		current.llink = newNode;
	}
	
	/**
	 * 
	 * @param head
	 * @param removed 需要被移除的節點
	 */
	public static void removing(NodeType head,NodeType removed){
		NodeType current = head.rlink;
		NodeType prev = null;
		
		while(current != head && removed.data != current.data){
			prev = current;
			current = current.rlink;
		}
		prev.rlink = current.rlink;
		current.rlink.llink = prev;
	}
	
	
	
	
	
	
	/**
	 * 插入新節點後，將新節點後面的節刪除
	 * 
	 * @param head
	 * @param newNode
	 */
	public static void insertAndremoving(NodeType head,NodeType newNode){
		NodeType current = head.rlink;
		NodeType prev = null;
		while(current != head && current.data < newNode.data){
			prev = current;
			current = current.rlink;
		}
		
		prev.rlink = newNode;
		newNode.llink = prev;
		
		newNode.rlink = current.rlink;
		current.rlink.llink = newNode;
		current = null;
	

	}
	/**
	 * 測試上面所寫方法
	 * @param args
	 */
	public static void main(String[] args) {
		NodeType head = new NodeType();
		NodeType a = new NodeType(55);
		NodeType b = new NodeType(64);
		NodeType c = new NodeType(78);
		NodeType d = new NodeType(85);
		NodeType e = new NodeType(98);
		NodeType f = new NodeType(112);
		
		head.llink = f;
		head.rlink = a;
		
		
		a.llink = head;
		a.rlink = b;

		b.llink = a;
		b.rlink = c;

		c.llink = b;
		c.rlink = d;

		d.llink = c;
		d.rlink = e;
		
		e.llink = d;
		e.rlink = f;
		
		f.llink = e;
		f.rlink = head;
		
		
	//	insert(head,new NodeType(84));
		insertAndremoving(head,new NodeType(84));
		getAllNodes(head);
		
		
	}
}