JAVA自己实现LinkedList

Posted 2022-07-22

package 集合.list.LinkedList; public class MyLinkedList //默认长度为0 private int size = 0; Node head = null; Node tail = null; public MyLinkedList() //添加元素的方法 public void add(Object obj) //创建Node Node node = new Node(obj, null, null); //先判断之前的尾部节点 if (size == 0) this.head = node; else Node temp; temp = this.tail; temp.next = node; node.prev = temp; this.tail = node; size++; //插入元素 public void add(int index, Object obj) //先判断索引是否合法 if (index > size || index < 0) throw new IndexOutOfBoundsException(); //判断插入位置 if (index == size) this.add(obj); return; //创建Node Node node = new Node(obj, null, null); Node temp = null; //如果插入是头部 if (index == 0) temp = this.head; this.head = node; node.next = temp; temp.prev = node; else // 如果插入中间位置 Node insertNode = indexOf(index); Node prev = insertNode.prev; node.prev = prev; node.next = insertNode; prev.next = node; insertNode.prev = node; size++; //删除指定索引元素 public void remove(int index) Node n; if (index == 0) n = head.next; head = n; n.prev = null; else if (index == size - 1) n = tail.prev; tail = n; n.next = null; else Node node = indexOf(index); Node prev = node.prev; Node next = node.next; prev.next = next; next.prev = prev; // node.prev = null; //node.next = null; size--; //删除第一个出现的元素 public void remove(Object obj) int index = indexOf(obj); if (index != -1) remove(index); //查找元素返回索引 public int indexOf(Object obj) //获取头节点 Node node = head; for (int i = 0; i < size; i++) if (node.value == obj || node.value != null && node.value.equals(obj)) return i; node = node.next; return -1; //查找指定索引的元素 public Node indexOf(int index) if (index == 0) return head; if (index == size - 1) return tail; Node n; if (index <= size / 2) //前一半 n = head; for (int i = 1; i < index; i++) n = n.next; else n = tail; for (int i = size - 2; i >= index; i--) n = n.prev; return n; //判断是否包含元素 public boolean cotains(Object obj) return indexOf(obj) != -1; //获取长度 public int getSize() return size; //判断是否为空 public boolean isEmpty() return size == 0; //清空链表 public void clear() //设置头尾节点为null,size=0 this.tail = null; this.head = null; size = 0; //通过索引修改数据 public void set(int index, Object obj) //先判断索引是否合法 if (index > size || index < 0) throw new IndexOutOfBoundsException(); indexOf(index).value = obj; //获取子链表 public MyLinkedList sublist(int fromIndex, int toIndex) //判断越界 //先判断索引是否合法 if (toIndex > size || fromIndex < 0) throw new IndexOutOfBoundsException(); MyLinkedList sublist = new MyLinkedList(); //先获取fromIndex处的节点 Node node = indexOf(fromIndex); for (int i = fromIndex; i < toIndex; i++) //将对于节点处的值加入到子链表中 sublist.add(node.value); //每次循环需要改变节点 node = node.next; return sublist; //重写toString @Override public String toString() StringBuilder sb = new StringBuilder(); sb.append("["); //获取节点 Node node = head; for (int i = 0; i < size; i++) if (i != size - 1) sb.append(node.value).append(","); else sb.append(node.value); node = node.next; sb.append("]"); return sb.toString(); //定义节点内部静态类 private static class Node //节点的数据 Object value; //节点的下一个地址 Node next; //上一个地址 Node prev; Node(Object value, Node prev, Node next) this.value = value; this.next = next; this.prev = prev;