无头双向链表的实现及测试代码
1.头插法
2.尾插法
3.任意位置插入,第一个数据节点为0号下标
4.查找是否包含关键字key是否在单链表当中
5.删除第一次出现关键字为key的节点
6.删除所有值为key的节点
7.得到单链表的长度
8.打印链表
9.清空链表
实现代码
class ListNode{
private int val;
private ListNode prev;
private ListNode next;
public ListNode(int val) {
this.val = val;
}
public int getVal() {
return val;
}
public ListNode getNext() {
return next;
}
public ListNode getPrev() {
return prev;
}
public void setVal(int val) {
this.val = val;
}
public void setPrev(ListNode prev) {
this.prev = prev;
}
public void setNext(ListNode next) {
this.next = next;
}
}
public class DoubleLinkedList {
private ListNode head;
private ListNode last;
//头插法
public void addFirst(int data){
ListNode node = new ListNode(data);
if(this.head == null){
this.head = node;
this.last = node;
}else {
//node.next = this.head;
node.setNext(this.head);
head.setPrev(node);
head = node;
}
}
public void display(){
ListNode cur =this.head;
while (cur != null){
System.out.print(cur.getVal() + " ");
cur = cur.getNext();
}
System.out.println();
}
// 尾插法
public void addLast(int data){
ListNode node = new ListNode(data);
if(this.head == null){
this.head = node;
this.last = node;
}else{
last.setNext(node);
node.setPrev(last);
this.last = node;
}
}
//任意位置插入,第一个数据节点为0号下标
public void addIndex(int index,int data){
if (index < 0 || index > size()){
return;
}
if(index == 0){
addFirst(data);
return;
}
if(index == size()){
addLast(data);
return;
}
ListNode cur = this.head;
while (index != 0){
cur = cur.getNext();
index--;
}
ListNode node =new ListNode(data);
node.setNext(cur);
node.setPrev(cur.getPrev());
node.getPrev().setNext(node);
cur.setPrev(node);
}
//查找是否包含关键字key是否在单链表当中
public boolean contains(int key){
ListNode cur = this.head;
while (cur != null){
if (cur.getVal() == key){
return true;
}
cur= cur.getNext();
}
return false;
}
public ListNode findNode(int key) {
ListNode cur = this.head;
while (cur != null) {
if(cur.getVal() == key) {
return cur;
}
cur = cur.getNext();
}
return null;
}
//删除第一次出现关键字为key的节点
public void remove(int key){
ListNode cur = this.findNode(key);
if(cur == null) {
return;
}
//
if(cur == this.head) {
this.head = this.head.getNext();
//this.head.prev = null;
this.head.setPrev(null);
return;
}
if(cur == this.last) {
cur.getPrev().setNext(null);
this.last = this.last.getPrev();
return;
}
cur.getPrev().setNext(cur.getNext());
cur.getNext().setPrev(cur.getPrev());
}
// 删除所有值为key的节点
public void removeAllKey(int key){
ListNode cur = this.head;
while (cur != null) {
if(cur.getVal() == key) {
if(cur == this.head) {
//头结点
this.head = this.head.getNext();
this.head.setPrev(null);
}else {
cur.getPrev().setNext(cur.getNext());
if(cur.getNext() != null) {
cur.getNext().setPrev(cur.getPrev());
}else {
//cur.next == null
this.last = this.last.getPrev();
}
}
}
cur = cur.getNext();
}
}
// 得到单链表的长度
public int size(){
ListNode cur = this.head;
int count = 0;
while (cur != null){
count++;
cur = cur.getNext();
}
return count;
}
public void clear(){
ListNode cur = this.head;
while (cur != null) {
ListNode curNext = cur.getNext();
cur.setNext(null);
cur.setPrev(null);
cur = curNext;
}
this.last = null;
this.head = null;
}
}
测试代码：
import com.sun.org.apache.xerces.internal.dom.PSVIAttrNSImpl;
import java.util.Arrays;
import java.util.LinkedList;
public class TestDemo {
public static void main(String[] args) {
DoubleLinkedList doubleLinkedList = new DoubleLinkedList();
doubleLinkedList.addLast(12);
doubleLinkedList.addLast(32);
doubleLinkedList.addLast(12);
doubleLinkedList.addLast(52);
doubleLinkedList.addLast(12);
doubleLinkedList.display();
System.out.println("===============");
doubleLinkedList.clear();
doubleLinkedList.display();
//doubleLinkedList.removeAllKey(12);
//doubleLinkedList.display();
//doubleLinkedList.remove(32);
//doubleLinkedList.display();
// doubleLinkedList.remove(12);
//doubleLinkedList.display();
//doubleLinkedList.addIndex(3,45);
//System.out.println(doubleLinkedList.contains(12));
}
}
清空方法的截图：
