雙向鏈表--Java實現

標籤：tla   int   雙向   節點   ==   遍曆   taf   ble   div   

  1 /*雙向鏈表特點：  2  *1.每個節點含有兩個引用，previos和next,支援向前或向後的遍曆(除前端節點)  3  *2.缺點插入或刪除的時候涉及到引用修改的比較多  4  *注意：下面的雙向鏈表其實也實現了雙端鏈表  5  *注意：在Java中多個引用可以指向同一個對象，也可以隨時改變引用的指向  6  *      關於修改引用細心一點就可以 引用A = 引用B 表示A引用指向B引用指向的對象  7  *應用:利用雙向鏈表可以實現雙端隊列  8  * */  9  10 public class MyDoubleLink { 11     private Link first; 12     private Link last; 13      14     public boolean isEmpty(){ 15         return first == null; 16     } 17      18     public void insertFirst(int key){ 19         Link newLink = new Link(key); 20         if(first == null){ 21             last = newLink; 22         } 23         else{ 24             first.previous = newLink; 25         } 26         newLink.next = first;//鏈未斷可以指向同一個 27         first = newLink; 28     } 29      30     public void insertLast(int key){ 31         Link newLink = new Link(key); 32         if(first == null){ 33             first = newLink; 34         } 35         else{ 36             last.next = newLink; 37             newLink.previous = last; 38         } 39         last = newLink; 40     } 41      42     //插入指定值的後邊---其實是一種尾巴插入--此時鏈表非空才可以操作 43     public boolean insertAfter(int key,int value){ 44         Link newLink = new Link(value); 45         Link current = first; 46         while(current.id != key){ 47             current = current.next; 48             if(current == null){ 49                 return false; 50             } 51         } 52         if(current == last){//find it at last item 53             newLink.next = null; 54             last = newLink; 55         } 56         else{ 57             newLink.next = current.next; 58             current.next.previous = newLink; 59         } 60         newLink.previous = current; 61         current.next = newLink; 62         return true; 63     } 64      65     public Link deleteFirst(){ 66         Link temp = first; 67         if(first.next == null){ 68             last = null; 69         } 70         else{ 71             first.next.previous = null; 72         } 73         first = first.next; 74         return temp; 75     } 76      77     public Link deleteLast(){ 78         Link temp = last; 79         if(first.next == null){ 80             first = null; 81         } 82         else{ 83             last.previous.next = null; 84         } 85         last = last.previous; 86         return temp; 87     } 88      89     //按照值進行刪除--可能存在找不到的時候 90     public Link delete(int key){ 91         Link current = first; 92         while(current.id != key ){ 93             current = current.next; 94             if(current == null){ 95                 return null; 96             } 97         } 98         if(current == first){//find it at first item並非只有一個節點 99             first = current.next;100         }101         else{  //find it not first item102             current.previous.next = current.next;103         }104         105         if(current == last){  //find it at last item106             last = current.previous;107         }108         else{ //find it not last109             current.next.previous = current.previous;110         }111         return current;112     }113     114     public void diaplayFirstToLast(){115         System.out.println("first to last");116         Link current = first;117         while(current != null){118             System.out.print(current.id + " ");119             current = current.next;120         }121         System.out.println();122     }123     124     public void displayLastToFirst(){125         System.out.println("last to first");126         Link current = last;127         while(current != null){128             System.out.print(current.id + " ");129             current = current.previous;130         }131         System.out.println();132     }133 }

 

雙向鏈表--Java實現