Java单链表和带附加头结点链表的插入删除操作

单链表的插入（头插，表中间插入，尾插）

//表头插入结点
newNode->next = first;
first = newNode;
//表中间插入结点和表尾插入结点
newNode->next = current->next;
current->next = newNode;

单链表的删除操作

//删除表头结点
del = first;
first = first->next;
delete del;
//删除表中间或尾部结点
del = current->next;
current->next = del->next;
delete del;

带附加头结点的单链表

在非空表的附加头结点后面和尾结点分别插入结点：

newNode->next = current->next;
current->next = newNode;

带附加头结点单链表的删除操作

del = current->next;
current->next = del->next;
delete del;

package shujujiegou;

public class ListNode3 {
	//头插法: newNode->next = first; first = newNode;
	//链表中间插入和链表中间插入：
	//newNode->next = current->next;current->next = newNode;

	/*
	  //用符合类表示单链表
		class List; //List类的前视声明
		class ListNode{ //结点类定义
			friend class List;
			private
				int data;
				ListNode next;
		};
		class List{ //class类定义
			public
			//链表公共操作
			.......
			private
				ListNode first; //链表头指针
		};
	
	 //用嵌套类表示单链表
	 class List{
	 	public
	 		//链表操作
	 		.......
	 	private
	 		class ListNode { //嵌套的类
	 		public 
	 			int data; //结点的数据域
	 			ListNode next; //结点的指针域
	 		};
	 		ListNode first; //单链表的头指针
	 }
	 */
	//单链表的插入算法
	public  static void Insert(int i,int x){
		//将新元素的x插入到第i各结点之后。i从1开始，i = 0表示插入到第一个节点之前。
		if(first == null || i == 0){ //插入空表或非空表第一个节点之前
			ListNode newNode = new ListNode(x); //建立一个新结点
			if(newNode == null){
				System.out.print("存储分配错误！");
			}
			newNode->next = first;
			first = newNode; //头插法，新结点成为第一个结点
		}else{
			ListNode current = first; //从第一个结点开始检测
			for(int k = 0;k<0;k++){
				if(currnt = null) break;
				else currnet = current->next;
			}
			if(current == null){
				System.out.print("无效的插入位置！");
				return false;
			}else{
				ListNode newNode = new ListNode(x);
				if(newNode == null){
					System.out.print("存储分配错误！");
				}
				newNode->next = current->next;
				current->next = newNode;
			}
		}
		return ture; //正常插入
	}
	
	//单链表的删除
	public static boolean Remove(int i,int x){
		//将链表中的第i的元素删去，i从0开始
		ListNode del,current;
		if(i<=1){
			del = first;
			first = first->next;
		}else{ //删除第一个结点时重新拉链
			current = first;
			for(int k = 1; k<i-1; i++){ //循链表找第i-1个结点
				if(current == null) break;
				else current = current->next;
			}
			if(current == null || current->next == null){ //空表或链太短
				System.out.print("无效的删除位置！");
				return false;
			}
			del = current->next; //删中间结点或尾结点时拉链
			current->next = del->next;
		}
		x = del->data; //取出被删结点中的数据值
		delete del;
	}
	public static void main(String[] args) {

	}
}