1，接口的定义
public interface MyList {
// 无头双向不循环链表实现
// 头插法
public void addFirst(int data);
// 尾插法
public void addLast(int data);
//任意位置插入,第一个数据节点为0号下标
public boolean addIndex(int index,int data);
//查找是否包含关键字key是否在单链表当中
public boolean contains(int key);
//删除第一次出现关键字为key的节点
public void remove(int key);
//删除所有值为key的节点
public void removeAllKey(int key);
//得到单链表的长度
public int size();
//打印链表
public void display();
//清空链表
public void clear();
}
2，实现类
//无头双向不循环链表
public class NoHeadTowListImpl implements MyList{
private Node head;
private int size;
public NoHeadTowListImpl() {
this.head = null;
this.size = 0;
}
//节点类
private class Node {
private int date;//数据
private Node pre;//前驱
private Node next;//后继
private Node(int date) {
this.date = date;
this.next = null;
this.pre = null;
}
}
//头插法
@Override
public void addFirst(int data) {
Node node = new Node(data);
if (isEmpty()) {
this.head = node;
}else {
node.next = this.head;
this.head.pre = node;
}
this.head = node;
this.size++;
}
private boolean isEmpty() {
return this.size == 0;
}
//找到最后一个节点
private Node lastNode() {
Node node = this.head;
while (node.next != null) {
node = node.next;
}
return node;
}
// 尾插法
@Override
public void addLast(int data) {
Node node = new Node(data);
if (isEmpty()) {
this.head = node;
}else {
Node last = lastNode();
last.next = node;
node.pre = last;
}
this.size++;
}
//找到index下标的节点
private Node searchIndex(int index) {
if (index < 0 || index > this.size) {
throw new IndexOutOfBoundsException("下标不合法！");
}
Node node = this.head;
int count = 0 ;
while (count < index) {
node = node.next;
count++;
}
return node;
}
//任意位置插入,第一个数据节点为0号下标
@Override
public boolean addIndex(int index, int data) {
if (index < 0 || index > this.size) {
throw new IndexOutOfBoundsException("下标不合法！");
}
Node node = new Node(data);
Node indexNode = searchIndex(index);
if (index == 0) {
addFirst(data);//头插法里面有size++
return true;
}else if (index == this.size){
addLast(data);
}else {
indexNode.pre.next = node;
node.pre = indexNode.pre;
node.next = indexNode;
indexNode.pre = node;
this.size++;
return true;
}
return false;
}
//查找是否包含关键字key是否在单链表当中
@Override
public boolean contains(int key) {
if (isEmpty()){
return false;
}else {
Node node = this.head;
while (node.date != key ) {
if (node.next == null){
return false;
}
node = node.next;
}
return true;
}
}
//找到关键字为key的节点
private Node searchKey(int key) {
Node node = this.head;
while (node.date != key) {
if (node.next == null) {
return null;
}
node = node.next;
}
return node;
}
//删除第一次出现关键字为key的节点
@Override
public void remove(int key) {
Node nodeKey = searchKey(key);
if (nodeKey == this.head) {
Node node = this.head.next;
node.pre = null;
this.head.next = null;
this.head = node;
this.size--;
}else if (nodeKey != null) {
//nodeKey不为最后一个节点时
if (nodeKey.next != null) {
nodeKey.pre.next = nodeKey.next;
nodeKey.next.pre = nodeKey.pre;
}else {
nodeKey.pre.next = null;
nodeKey.pre = null;
}
this.size--;
}
}
//删除所有值为key的节点
@Override
public void removeAllKey(int key) {
Node node = this.head.next;
while (node != null) {
while (node.date == key) {
Node nodePre = node.pre;
if (node.next != null) {
node.pre.next = node.next;
node.next.pre = node.pre;
}else {
node.pre.next = null;
node.pre = null;
}
node = nodePre;
this.size--;
}
node = node.next;
}
if (this.head.date == key ) {
node = this.head.next;
node.pre = null;
this.head.next = null;
this.head = node;
this.size--;
}
}
//得到单链表的长度
@Override
public int size() {
return this.size;
}
//打印链表
@Override
public void display() {
if (this.size == 0) {
System.out.println("链表为空！");
} else {
Node node = this.head;
for (int i = 0; i < this.size; i++) {
System.out.print(node.date + " ");
node = node.next;
}
System.out.println();
}
}
//清空链表
@Override
public void clear() {
Node node = this.head;
while (this.head != null) {
node.pre = null;
this.head.next = null;
this.head = node;
if (this.head.next != null) {
node = this.head.next;
}else {
this.head = null;
}
}
this.size = 0;
}
}
3，测试类
public class NoHeadTowListTest {
public static void main(String[] args) {
NoHeadTowListImpl noHeadTowList = new NoHeadTowListImpl();
noHeadTowList.addIndex(0,2);
noHeadTowList.addFirst(1);
noHeadTowList.addFirst(1);
noHeadTowList.addLast(3);
noHeadTowList.addIndex(0,2);
noHeadTowList.addIndex(noHeadTowList.size(),2);
System.out.println(noHeadTowList.size());
noHeadTowList.display();
System.out.println(noHeadTowList.contains(2));
noHeadTowList.removeAllKey(1);
noHeadTowList.display();
noHeadTowList.remove(2);
noHeadTowList.display();
noHeadTowList.clear();
noHeadTowList.display();
}
}
4，运行结果
6
2 1 1 2 3 2
true
2 2 3 2
2 3 2
链表为空！
Process finished with exit code 0
