MyLinkedList1.java文件
class ListNode {
public int val;
public ListNode prev;
public ListNode next;
public ListNode(int val) {
this.val = val;
}
}
public class MyLinkedList1 {
//实现带头双向不循环链表
public ListNode last;
public ListNode head = new ListNode(-1);
//打印链表
public void display() {
if (head.next == null) {
return;
}
ListNode cur = head.next;
while (cur != null) {
System.out.print(cur.val+ " ");
cur = cur.next;
}
System.out.println();
}
//得到双链表的长度
public int size() {
int count = 0;
ListNode cur = this.head;
while (cur != null) {
count++;
cur = cur.next;
}
return count-1;
}
//实现头插法
public void addList(int data) {
ListNode node = new ListNode(data);
if (head.next == null) {
head.next = node;
node.prev = head;
last = node;
}else {
node.next = head.next;
node.prev = head;
head.next.prev = node;
head.next = node;
}
}
//查找是否包含关键字key是否在双链表当中
public boolean contains(int key){
ListNode cur = head.next;
while (cur != null) {
if (cur.val == key) {
return true;
}
cur = cur.next;
}
return false;
}
//尾插法
public void addLast(int data){
ListNode node = new ListNode(data);
if (head.next == null) {
head.next = node;
node.prev = head;
last = node;
}else {
last.next = node;
node.prev = last;
last = node;
}
}
//删除第一次出现关键字为key的节点
public void remove(int key){
if (head.next == null) {
return;
}
ListNode cur = head.next;
while (cur != null) {
if (cur.val == key) {
if (cur == head.next) {
head.next = cur.next;
if (cur.next != null){
cur.next.prev = head;
}else {
last = head;
}
}
else if (cur == last) {
cur.prev.next = null;
last = cur.prev;
}else {
cur.prev.next = cur.next;
cur.next.prev = cur.prev;
}
return;
}
cur = cur.next;
}
}
//删除出现关键字为key的所有节点
public void removeAllKey(int key){
if (head.next == null) {
return;
}
ListNode cur = head.next;
while (cur != null) {
if (cur.val == key) {
if (cur == head.next) {
head.next = cur.next;
if (cur.next != null){
cur.next.prev = head;
}else {
last = head;
}
}
else if (cur == last) {
cur.prev.next = null;
last = cur.prev;
}else {
cur.prev.next = cur.next;
cur.next.prev = cur.prev;
}
}
cur = cur.next;
}
}
//查找下标为index的节点，返回节点
public ListNode searchIndex (int index) {
if (index < 0 || index > size()) {
System.out.println("index的位置不合法！");
return null;
}
ListNode cur = head.next;
while (index != 0) {
index--;
cur = cur.next;
}
return cur;
}
//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 (head.next == null) {
return;
}
if (index == 0) {
addList(data);
return;
}
if (index == size()) {
addLast(data);
return;
}
ListNode cur = searchIndex(index);
ListNode node = new ListNode(data);
if (cur == null) {
return;
}
node.next = cur;
node.prev = cur.prev;
cur.prev.next = node;
cur.prev = node;
}
//暴力的做法是直接将head和last直接置为null
//温柔的做法将所有节点置为null
public void clear() {
ListNode cur = head;
ListNode curNext;
while (cur != null) {
curNext = cur.next;
cur.prev = null;
cur.next = null;
cur = curNext;
}
head = null;
last = null;
}
}
TestDemo.java文件
public class TestDemo1 {
public static void main(String[] args) {
MyLinkedList1 myLinkedList1 = new MyLinkedList1();
myLinkedList1.addLast(1);
myLinkedList1.addLast(2);
myLinkedList1.addLast(2);
myLinkedList1.addLast(4);
myLinkedList1.addLast(5);
myLinkedList1.display();
System.out.println(myLinkedList1.size());
System.out.println(myLinkedList1.contains(1));
myLinkedList1.addIndex(2,7);
// myLinkedList1.remove(1);
// myLinkedList1.display();
myLinkedList1.removeAllKey(1);
myLinkedList1.display();
}
}