package LinkedList;
public class LinkedList<E> {
//内部类
private class Node {
public E e;
public Node next;
// 用户传来e 和 next
public Node(E e, Node next) {
this.e = e;
this.next = next;
}
// 用户传来只传来e
public Node(E e) {
this(e, null);
}
// 用户没有传任何参数
public Node() {
this(null, null);
}
@Override
public String toString() {
return e.toString();
}
}
//虚拟头结点
private Node dummyhead;
//记录链表中有多少个元素
private int size;
//对于一个空的链表来说 他是存在一个空的节点的,这个节点就是唯一的虚拟头结点
public LinkedList() {
dummyhead = new Node(null, null);
size = 0;
}
//获取当前链表中元素的个数
public int getSize() {
return size;
}
//返回链表是否为空
public boolean isEmpty() {
return size == 0;
}
//在链表的index(0-based)位置添加新的元素e
public void add(int index, E e) {
if (index < 0 || index > size) {
throw new IllegalArgumentException("Add failed. Illegal index");
}
Node prev = dummyhead;
for (int i = 0; i < index; i++) {
//prev一直向前移动 直到移动到index-1的位置
prev = prev.next;
}
//新插入的node prev.next = new Node(e, prev.next); 与下面三句话等价
Node node = new Node(e);
node.next = prev.next;
prev.next = node;
size++;
}
//在链表的头插入新的元素
public void addFirst(E e) {
add(0, e);
}
//在链表的尾插入新的元素
public void addLast(E e) {
add(size, e);
}
// 获得链表的第index(0-based)个位置的元素
// 在链表中不是一个常用的操作
public E get(int index) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("get failed. Illegal index");
}
Node cur = dummyhead.next;
for (int i = 0; i < index; i++) {
cur = cur.next;
}
return cur.e;
}
//获取列表的第一个元素
public E getFirst() {
return get(0);
}
//获取列表的最后一个元素
public E getLast() {
return get(size - 1);
}
// 修改链表的第index(0-based)个位置的元素为e
// 在链表中不是一个常用的操作
public void set(int index, E e) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("Set failed. Illegal index");
}
Node cur = dummyhead.next;
for (int i = 0; i < index; i++) {
cur = cur.next;
}
cur.e = e;
}
// 查找链表中是否有元素e
public boolean contains(E e) {
Node cur = dummyhead.next;
while (cur != null) {
if (cur.e.equals(e)) {
return true;
}
cur = cur.next;
}
return false;
}
//从链表中删除index(0-based)位置的元素,返回删除的元素e
public E remove(int index) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("Remove failed. Illegal index");
}
Node prev = dummyhead;
for (int i = 0; i < index; i++) {
prev = prev.next;
}
Node retNode = prev.next;
prev.next = retNode.next;
retNode.next= null;
size--;
return retNode.e;
}
public E removeFirst() {
return remove(0);
}
public E removeLast() {
return remove(size - 1);
}
@Override
public String toString() {
StringBuffer res = new StringBuffer();
Node cur = dummyhead.next;
while (cur != null) {
res.append(cur + "->");
cur = cur.next;
}
// 与上面等价
// for (Node cur = dummyhead.next; cur != null; cur = cur.next) {
// res.append(cur + "->");
// }
res.append("NULL");
return res.toString();
}
public static void main(String[] args) {
LinkedList<Integer> linkedList = new LinkedList<Integer>();
for (int i = 0; i < 5; i++) {
linkedList.addFirst(i);
System.out.println(linkedList);
}
linkedList.add(2,666);
System.out.println(linkedList);
linkedList.remove(2);
System.out.println(linkedList);
linkedList.removeFirst();
System.out.println(linkedList);
linkedList.removeLast();
System.out.println(linkedList);
}
}
数据结构-链表(二、底层实现---源码)
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转载自blog.csdn.net/qq_43229543/article/details/104033614
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