Java 链表操作

转自：http://www.jb51.net/article/71885.htm

 public class LinkList{
 	class Node{
 		int data;
 		Node next;
 		public Node(int data){
 			this.data=data;
 		}
 	}
 	

 	public  Node head;
 	public Node current;
//方法：向链表中添加数据
 public void add(int data){
 	if(head==null){//如果头节点为空，说明这个链表还没创建。把新的结点赋值给头节点
 		head=new Node(data);
 		current=head;
     } 
 	else{
 		//创建新的节点，放在当前节点的后面
 		current.next=new Node(data);
 		//把链表的当前索引向后移动一位
 		current=current.next;
 	}
 }
 //方法：遍历链表(打印输出链表)
 public void print(Node node){
 	if(node==null){
 		System.out.print("Eorr");
 		return ;
 	}
 	current=node;
 	while(current!=null){
 		System.out.println(current.data);
 		current=current.next;
 	}
 }
 //方法：获取单链表的长度
 public int getLength(Node head){
 	if(head==null)
 		return 0;
 	int length=0;
 	Node current=head;
 	while(current!=null){
 		length++;
 		current=current.next;
 	}
 	return length;
 }

 //查找单链表中的倒数第k个节点；
 //遍历 求出链表长度size
 public int findLastNode(int index){
 	if(head==null){
 		return -1;
 	}
 	int size=0;
 	current=head;
 	while(current!=null){
 		size++;
 		current=current.next;
 	}
 	current=head;
 	for(int i=0;i<size-index;i++){
 		current=current.next;
 	}
 	return  current.data;

 }
 //不遍历链表的长度
 //声明两个指针first 和second
//
public Node findLastNode(Node head,int index){
	if(head==null)
		return null;
	
	Node first=head;
	Node second=head;
	//让second 节点向后挪index个位置
	for(int i=0;i<index;i++){
		second=second.next;
	} 
	while(second!=null){
		first=first.next;
		second=second.next;
	}
	return first;
}
//再次改进 （考虑到k大于链表中节点个数时候抛出异常
//1：k=0 2：k>size
public Node findLastNode_3(Node head ,int k){
	if(k==0||head==null)
		return null;

	Node first =head;
	Node second=head;
	//让second结点向后挪k-1个位置
	for(int i=0;i<k;i++){
		second=second.next;	
	if(second==null){//k>size
		return  null;	
		}
	}
	while(second.next!=null){
		first=first.next;
		second=second.next;
	}
	return first;

}
//查找单链表中的中间节点
public Node findMidNode(Node haed){
	if(head==null){
		System.out.println("Error");
		return null;
	}
	Node first=head;
	Node second=head;
	while(second!=null&&second.next!=null){
		first=first.next;
		second=second.next.next;
	}
	return  first;

}//6 renturn 4


//合并两个有序链表 合并后依然有序
public Node mergeLinkList(Node head1,Node head2){
	if(head1==null&&head2==null)
		return null;
	if(head1==null){
		return head2;
	}
	if(head2==null)
		return head1;
	Node head;
	Node current;
	if(head1.data>head2.data){
		head=head1;
		current=head1;
		head1=head1.next;
	}
	else{
		head=head2;
		current=head2;
		head2=head2.next;
	}
	while(head1!=null&&head2!=null){
		if(head1.data<head2.data){
			current.next=head1;
			current=head1;
			head1=head1.next;
		}
		else{
			current.next=head2;
			current=head2;
			head2=head2.next;
		}
	}
		if(head1!=null){
			current.next=head1;
		}
		if(head2!=null){
			current.next=head2;
		}
		
	
		return  head;
}
//单链表的反转
public Node reverseList(Node head){
	if(head==null||head.next==null)
		return head; 
	Node current=head;
	Node next=null;
	Node reverseHead=null;
	while(current!=null){
		next=current.next;
		current.next=reverseHead;
		reverseHead=current;
		current=next;
	}
	return reverseHead;
}


public static void main(String[] args) {
	LinkList list1=new LinkList();
	//向LinkList中添加数据
	LinkList list2=new LinkList();
	for(int i=0;i<6;i++){
		list2.add(i);
	}
	list1.head=list2.reverseList(list2.head);
	list1.print(list1.head);
	for(int i=0;i<8;i++){
		list2.add(i);
	}
	LinkList a=new LinkList();
	a.head=a.mergeLinkList(list1.head,list2.head);
	a.print(a.head);
}
}