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Java中的双向链表可以通过定义一个Node类来实现，该类包含一个值和两个指针，分别指向前一个节点和后一个节点。具体实现如下：
public class DoublyLinkedList { private Node head; // 链表头节点 private Node tail; // 链表尾节点 // 节点类 private class Node { private int value; private Node prev; private Node next; public Node(int value) { this.value = value; this.prev = null; this.next = null; } } // 在链表末尾添加节点 public void add(int value) { Node newNode = new Node(value); if (head == null) { head = newNode; tail = newNode; } else { newNode.prev = tail; tail.next = newNode; tail = newNode; } } // 在指定位置插入节点 public void insert(int index, int value) { if (index < 0 || index > size()) { throw new IndexOutOfBoundsException("Invalid index"); } if (index == 0) { Node newNode = new Node(value); newNode.next = head; head.prev = newNode; head = newNode; } else if (index == size()) { add(value); } else { Node cur = head; for (int i = 0; i < index; i++) { cur = cur.next; } Node newNode = new Node(value); newNode.prev = cur.prev; newNode.next = cur; cur.prev.next = newNode; cur.prev = newNode; } } // 删除指定位置的节点 public void remove(int index) { if (index < 0 || index >= size()) { throw new IndexOutOfBoundsException("Invalid index"); } if (index == 0) { head = head.next; head.prev = null; } else if (index == size() - 1) { tail = tail.prev; tail.next = null; } else { Node cur = head; for (int i = 0; i < index; i++) { cur = cur.next; } cur.prev.next = cur.next; cur.next.prev = cur.prev; } } // 获取指定位置的节点值 public int get(int index) { if (index < 0 || index >= size()) { throw new IndexOutOfBoundsException("Invalid index"); } Node cur = head; for (int i = 0; i < index; i++) { cur = cur.next; } return cur.value; } // 返回链表的大小 public int size() { int count = 0; Node cur = head; while (cur != null) { count++; cur = cur.next; } return count; } } 使用示例：
public class Main { public static void main(String[] args) { DoublyLinkedList list = new DoublyLinkedList(); list.add(1); list.add(2); list.add(3); System.out.println("Size: " + list.size()); // 输出：Size: 3 list.insert(1, 4); System.out.println("Size: " + list.size()); // 输出：Size: 4 System.out.println("Element at index 1: " + list.get(1)); // 输出：Element at index 1: 4 list.remove(2); System.out.println("Size: " + list.size()); // 输出：Size: 3 System.out.println("Element at index 2: " + list.get(2)); // 输出：Element at index 2: 3 } } 以上代码实现了一个简单的双向链表，并提供了添加、插入、删除和获取节点的功能。
