单链表的操作
本方法实现了以下操作:
- 表头添加元素
- 表头删除元素
- 查找指定元素
- 删除指定元素
- 链表反转 - 遍历实现
- 链表反转 - 递归实现
- 链表反转- LinkedList的反转
- 遍历求元素个数
public class SingleLinkedList {
private int size;//链表节点的个数
private Node head;//头节点
public SingleLinkedList(){
size = 0;
head = null;
}
//链表的每个节点类
private class Node{
private Object data;//每个节点的数据
private Node next;//每个节点指向下一个节点的连接
public Node(Object data){
this.data = data;
}
}
//在链表头添加元素
public Object addHead(Object obj){
Node newHead = new Node(obj);
if(size == 0){
head = newHead;
}else{
newHead.next = head;
head = newHead;
}
size++;
return obj;
}
//在链表头删除元素
public Object deleteHead(){
Object obj = head.data;
head = head.next;
size--;
return obj;
}
//查找指定元素,找到了返回节点Node,找不到返回null
public Node find(Object obj){
Node current = head;
int tempSize = size;
while(tempSize > 0){
if(obj.equals(current.data)){
return current;
}else{
current = current.next;
}
tempSize--;
}
return null;
}
//删除指定的元素,删除成功返回true
public boolean delete(Object value){
if(size == 0){
return false;
}
Node current = head;
Node previous = head;
while(current.data != value){
if(current.next == null){
return false;
}else{
previous = current;
current = current.next;
}
}
//如果删除的节点是第一个节点
if(current == head){
head = current.next;
size--;
}else{//删除的节点不是第一个节点
previous.next = current.next;
size--;
}
return true;
}
//判断链表是否为空
public boolean isEmpty(){
return (size == 0);
}
//显示节点信息
public void display(){
if(size >0){
Node node = head;
int tempSize = size;
if(tempSize == 1){//当前链表只有一个节点
System.out.println("["+node.data+"]");
return;
}
while(tempSize>0){
if(node.equals(head)){
System.out.print("["+node.data+"->");
}else if(node.next == null){
System.out.print(node.data+"]");
}else{
System.out.print(node.data+"->");
}
node = node.next;
tempSize--;
}
System.out.println();
}else{//如果链表一个节点都没有,直接打印[]
System.out.println("[]");
}
}
// 链表反转 - 遍历法 - @Chase
public void reverse1() {
//上一个节点
Node previousNode = null;
//当前节点
Node currentNode = head;
//头节点
Node headNode = null;
while (currentNode != null) {
//将当前节点的下一个节点保存起来
Node nextNode = currentNode.next;
//判断当前节点是否为尾节点
if (nextNode == null) {
headNode = currentNode;
}
//将当前节点指向上一个节点,反转
currentNode.next = previousNode;
//上一个节点保存当前节点的信息,即上一个节点指向当前节点的下一个节点
previousNode = currentNode;
//当前节点变为当前节点的下一个节点
currentNode = nextNode;
}
head = headNode;
}
//链表反转- 递归 - @Chase
static Node reverseLinkedList(Node node) {
//判断尾节点和空链表
if (node == null || node.next == null) {
return node;
} else {
//递归
Node headNode = reverseLinkedList(node.next);
node.next.next = node;
node.next = null;
return headNode;
}
}
public void reverse2() {
head = reverseLinkedList(head);
}
//遍历求个数 - @Chase
public int findall(){
Node current = head;
int tempSize = size;
int sum = 1;
while(current!=null){
System.out.println(sum);
sum+=1;
current = current.next;
}
return sum;
}
}