1 package MutuLink;  2  3 public class MyList {  4 private Node head;  5 private Node tail;  6 private int size = 0;  7  8 public MyList() {  9 head = new Node();  10 tail = new Node();  11 head.next =null;  12 tail.pre = null;  13  }  14  15 public boolean empty() {  16 if (head.next == null)  17 return true;  18 return false;  19  }  20 //找到所找下标节点的前一个节点  21 public Node findpre(int index){  22 Node rnode = head;  23 int dex = -1;  24 while(rnode.next != null){  25 //找到了插入节点的上一个节点  26 if( dex== index - 1){  27 return rnode;  28  }  29 rnode = rnode.next;  30 dex++;  31  }  32 return null;  33  }  34 public Node findthis(int index){  35 Node rnode = head;  36 //把rnode想象为指针，dex为指向的下标，这个地方很容易错，因为当指向最后一个节点时没有判断IF就跳出循环了  37 int dex = -1;  38 while(rnode.next != null){  39 if(dex == index)  40 return rnode;  41 rnode = rnode.next;  42 dex++;  43  }  44 if(dex == size - 1){  45 return rnode;  46  }  47 // Node test = new Node(new Students(“haha”,1,2));  48 return null;  49  }  50  51 // 往链表末尾加入节点  52 public void add(Object e) {  53 Node node = new Node(e);  54 Node rnode = head;  55 //如果是空链表的话插入一个节点，这个节点的pre不能指向上一个节点，必须指空  56 if (this.empty()) {  57 rnode.next = node;  58 rnode.next.pre = null;  59 tail.pre = node;  60 size++;  61 } else {  62 while (rnode.next != null)  63 rnode = rnode.next;  64 rnode.next = node;  65 node.pre = rnode;  66 tail.pre = node;  67 size++;  68  }  69  }  70 //往链表的某一个标插入一个节点  71 public boolean add(int index,Object e){  72 if(index <0||index>=size)  73 return false;  74 Node node = new Node(e);  75 Node prenode = this.findpre(index);  76 node.next = prenode.next;  77 prenode.next.pre = node;  78 prenode.next = node;  79 node.pre = prenode;  80 size++;  81 return true;  82  }  83 public boolean add(int index,MyList myl){  84 if(index <0 || index >= size)  85 return false;  86 Node prenode = this.findpre(index);  87 // myl.tail.pre.next = prenode.next;  88 // prenode.pre = myl.tail.pre;  89 // tail.pre = null;  90 // prenode.next = myl.head.next;  91 // myl.head.next.pre = prenode;  92 // head.next = null;  93 myl.tail.pre.next = prenode.next;  94 prenode.next.pre = myl.tail.pre.pre;  95 myl.head.next.pre = prenode.pre;  96 prenode.next = myl.head.next;  97 myl.head = null;  98 myl.tail = null;  99 size+=myl.size; 100 return true; 101  } 102
 103 public Object remove(int index){ 104 Object ob= this.get(index); 105 if(index <0 || index >= size) 106 return null; 107 //特殊情况，当移除节点是最后一个节点的时候 108 //较为复杂通过画图来写代码 109 if(index == size - 1){ 110 Node prenode = this.findpre(index); 111 this.tail.pre = this.tail.pre.pre; 112 this.tail.pre.next.pre = null; 113 this.tail.pre.next =null; 114 size–; 115 return ob; 116  } 117 //比较复杂，通过画图解决 118 else{ 119 Node prenode = this.findpre(index); 120 prenode.next = prenode.next.next; 121 prenode.next.pre.next = null; 122 prenode.next.pre = prenode.next.pre.pre; 123 size–; 124 return ob; 125  } 126  } 127
 128
 129 public Object get(int index){ 130 Node thisnode = this.findthis(index); 131 return thisnode.e; 132  } 133 public int size(){ 134 return size; 135  } 136 }

讯享网