LinkedList手写1

LinkedList的底层是基于链表实现的，所以查询慢，增删改快，但是线程不安全，效率较高。

LinkedList类

  1 /**
  2  * remove方法
  3  * add方法
  4  * get方法
  5  * getNode方法
  6  * @author HQ
  7  * @e-mail ahmashq95@gmail.com
  8  * @date 2018/11/2.
  9  */
 10 public class LinkedList01 {
 11 
 12     private Node first;
 13     private Node last;
 14     private int size;
 15 
 16     public void remove(int index) {
 17         Node temp = getNode(index);
 18         if (temp != null) {
 19             Node up = temp.previous;
 20             Node down = temp.next;
 21             if (up != null) {
 22                 up.next = down;
 23             }
 24             if (down != null) {
 25                 down.previous = up;
 26             }
 27 
 28             //被删除的元素是第一个元素时
 29             if(index==0){
 30                 first=down;
 31             }
 32             //被删除的元素是最后一个元素时
 33             if(index==size-1){
 34                 last=up;
 35             }
 36             size--;
 37         }
 38     }
 39 
 40     // [ ]
 41     //["a","b"]
 42     public void add(Object object) {
 43         Node node = new Node(object);
 44 
 45         if (first == null) {
 46 
 47             node.previous = null;
 48             node.next = null;
 49 
 50             first = node;
 51             last = node;
 52         } else {
 53             node.previous = last;
 54             node.next = null;
 55 
 56             last.next = node;
 57             last = node;
 58         }
 59         size++;
 60     }
 61 
 62     @Override
 63     public String toString() {
 64         StringBuilder stringBuilder = new StringBuilder("[");
 65 
 66 
 67         Node temp = first;
 68         while (temp != null) {
 69             stringBuilder.append(temp.element + ",");
 70             temp = temp.next;
 71         }
 72         stringBuilder.setCharAt(stringBuilder.length() - 1, ']');
 73 
 74         return stringBuilder.toString();
 75     }
 76 
 77     public Object get(int index) {
 78         if (index < 0 || index > size - 1) {
 79             throw new RuntimeException("索引位置不合法" + index);
 80         }
 81 
 82         Node temp = getNode(index);
 83         return temp != null ? temp.element : null;
 84 
 85     }
 86 
 87     public Node getNode(int index) {
 88         Node temp = null;
 89         //size>>1 相当于除以2
 90         if (index < (size >> 1)) {
 91             temp = first;
 92             for (int i = 0; i < index; i++) {
 93                 temp = temp.next;
 94             }
 95 
 96         } else {
 97             temp = last;
 98             for (int i = size - 1; i > index; i--) {
 99                 temp = temp.previous;
100 
101             }
102         }
103         return temp;
104 
105     }
106 
107     public static void main(String[] args) {
108         LinkedList01 list01 = new LinkedList01();
109 
110         list01.add("a");
111         list01.add("b");
112         list01.add("c");
113         list01.add("d");
114         list01.add("e");
115         list01.add("f");
116 
117         System.out.println(list01);
118         System.out.println("------------");
119         list01.remove(0);
120         System.out.println(list01);
121         System.out.println(list01.size);
122         System.out.println("------------");
123 
124         list01.remove(0);
125         System.out.println(list01);
126         System.out.println(list01.size);
127         System.out.println("------------");
128 
129         list01.remove(0);
130         System.out.println(list01);
131         System.out.println(list01.size);
132     }
133 }

 

Node类

 1 /**
 2  * @author HQ
 3  * @e-mail ahmashq95@gmail.com
 4  * @date 2018/11/2.
 5  */
 6 public class Node {
 7     Node previous;//Last Node
 8     Node next;//next Node
 9     Object element;
10 
11     public Node(Node previous, Node next, Object element) {
12         super();
13         this.previous = previous;
14         this.next = next;
15         this.element = element;
16     }
17 
18     public Node(Object element) {
19         this.element = element;
20     }
21 }

 

posted @ 2018-11-07 10:22  dreaming达摩  阅读(91)  评论(0)    收藏  举报