在写了MyArrayList类之后，也写了个MyLinkedList类，这个类当时只实现了基本的链表操作，很多功能只求能够实现而没有考虑优化，好多细节没有考虑周到。今天重看了那个破烂不堪的类，优化改进了一下。主要有：1，添加类的int length属性，实时记录链表的长度。2，添加类的Node lastNode属性，记录最后一个结点，这样在链表添加操作时就不用每次都遍历一遍，提高了add操作的效率。3，完善方法使用规范，添加异常处理
包下包含MyList.java接口类，Node.java结点类，MyLinkedList.java链表类。（第一个是用循环链表解决约瑟夫问题的类，与本文无关）
结点类 Node.java
1 package cn.ftf.mylinkedlist; 2 /* 3 * 结点类 4 */ 5 public class Node { 6 public Object obj; 7 public Node next; 8 public Node() { 9 super(); 10 } 11 public Node(Object obj, Node next) { 12 super(); 13 this.obj = obj; 14 this.next = next; 15 } 16 public Node(Object obj) { 17 super(); 18 this.obj = obj; 19 } 20 }List接口类 MyList.java
1 package cn.ftf.mylinkedlist; 2 3 public interface MyList { 4 public void clear(); 5 public boolean isEmpty(); 6 public int length(); 7 public Object get(int i) throws Exception; 8 public void add(Object obj); 9 public void inset(int i,Object obj) throws Exception; 10 public void remove(int i) throws Exception; 11 public int indexOf(Object obj); 12 public void display(); 13 }链表类 MyLinkedList.java
1 package cn.ftf.mylinkedlist; 2 /* 3 * 链表类 4 */ 5 public class MyLinkedList implements MyList{ 6 private Node head; //头结点 7 private int length=0; //实时记录链表长度 8 private Node lastNode=null; //记录最后一个结点，方便插入新结点，就不用遍历了 9 10 public MyLinkedList() { 11 this.head = new Node(); 12 } 13 14 @Override 15 public void clear() { 16 this.head=new Node(); 17 this.length=0; 18 this.lastNode=null; 19 } 20 21 @Override 22 public boolean isEmpty() { 23 return head.next==null; 24 } 25 26 @Override 27 public int length() { 28 return this.length; 29 } 30 31 @Override 32 public Object get(int i) throws Exception { 33 if(i<0||i>length-1) { 34 return null; 35 } 36 Node p = this.head; 37 for(int a=0;a<i+1;a++) { 38 p=p.next; 39 } 40 return p.obj; 41 } 42 43 @Override 44 public void add(Object obj) { 45 // TODO Auto-generated method stub 46 if(this.lastNode==null) { 47 Node p = this.head; 48 Node newNode=new Node(obj); 49 p.next=newNode; 50 this.lastNode=newNode; 51 }else { 52 Node newNode=new Node(obj); 53 this.lastNode.next=newNode; 54 this.lastNode=newNode; 55 } 56 this.length++; 57 } 58 59 @Override 60 public void inset(int i, Object obj) throws Exception { 61 if(i<0||i>length) { 62 throw new Exception("操作位置非法！"); 63 } 64 Node p = this.head; 65 Node newNode=new Node(obj); 66 for(int a=0;a<i;a++) { 67 p=p.next; 68 } 69 newNode.next=p.next; 70 p.next=newNode; 71 this.length++; 72 } 73 74 @Override 75 public void remove(int i) throws Exception { 76 if(i<0||i>length-1) { 77 throw new Exception("操作位置非法！"); 78 } 79 Node p = this.head; 80 for(int a=0;a<i;a++) { 81 p=p.next; 82 } 83 p.next=p.next.next; 84 if(i==this.length-1) { 85 this.lastNode=p; 86 } 87 this.length--; 88 } 89 90 @Override 91 public int indexOf(Object obj) { 92 int a=0; 93 Node p = this.head; 94 while(p.next!=null) { 95 p=p.next; 96 if(obj.equals(p.obj)) { 97 return a; 98 } 99 a++; 100 } 101 return -1; 102 } 103 104 @Override 105 public void display() { 106 Node p=head; 107 while(p.next!=null) { 108 System.out.print(p.next.obj+" "); 109 p=p.next; 110 } 111 System.out.println(); 112 } 113 114 //主方法测试用 115 public static void main(String[] args) throws Exception { 116 MyLinkedList li=new MyLinkedList(); 117 System.out.println(li.isEmpty()); 118 li.add("hello"); 119 li.add("word!"); 120 System.out.println(li.isEmpty()); 121 System.out.println(li.length()); 122 li.display(); 123 System.out.println(li.get(1)); 124 li.inset(1, "hahaha"); 125 li.display(); 126 li.remove(2); 127 li.add(123); 128 li.add("word!"); 129 li.display(); 130 System.out.println(li.indexOf(123)); 131 System.out.println(li.length); 132 } 133 134 }测试结果：
转载于:https://www.cnblogs.com/fangtingfei/p/11524587.html
