java开始到熟悉103-104

本次内容：linkedlist（）

此次是承接上次arraylist（），自己实现linkedlist（）（内容较少）

  1 package list;

  2 /**

  3  * 自定义linkedlist类

  4  * @author acer

  5  *

  6  */

  7 public class mylinkedlist {

  8     private Node first;

  9     private Node last;

 10     private int size;

 11     public void add(Object obj)

 12     {

 13         Node n=new Node();

 14         if(first==null)

 15         {

 16             n.setPrevious(null);

 17             n.setObj(obj);

 18             n.setNext(null);

 19             first=n;

 20             last=n;

 21         }

 22         else

 23         {

 24             n.setPrevious(last);

 25             n.setObj(obj);

 26             n.setNext(null);

 27             last.setNext(n);

 28             last=n;

 29         }

 30         size++;

 31     }

 32     public void add(int index,Object obj)

 33     {

 34         Node temp=null;

 35         Node newNode=new Node();

 36         newNode.setObj(obj);

 37         if(first!=null)

 38         {

 39             temp=first;

 40             for(int i=0;i<index;i++)

 41             {

 42                 temp=temp.getNext();

 43             }

 44         }

 45         newNode.setPrevious(temp.getPrevious());

 46         temp.getPrevious().setNext(newNode);

 47         newNode.setNext(temp);

 48         temp.setPrevious(newNode);

 49         size++;

 50

 51     }

 52     public Object get(int index)

 53     {

 54         rangeCheck(index);

 55         Node temp=null;

 56         if(first!=null)

 57         {

 58             temp=first;

 59             for(int i=0;i<index;i++)

 60             {

 61                 temp=temp.getNext();

 62             }

 63         }

 64         return temp.getObj();

 65     }

 66     public void removefirst()

 67     {

 68         Node temp=null;

 69         temp=first;

 70         temp=temp.getNext();

 71         temp.setPrevious(null);

 72         first.setNext(null);

 73         first=temp;

 74     }

 75     public void remove(int index)

 76     {

 77         rangeCheck(index);

 78         Node temp=null;

 79         if(first!=null)

 80         {

 81             temp=first;

 82             for(int i=0;i<index;i++)

 83             {

 84                 temp=temp.getNext();

 85             }

 86         }

 87         if(temp!=null)

 88         {

 89             Node pre=temp.getPrevious();

 90             Node ne=temp.getNext();

 91             pre.setNext(ne);

 92             ne.setPrevious(pre);

 93             size--;

 94         }

 95

 96     }

 97     public void rangeCheck(int index)

 98     {

 99         if(index<0||index>=size)

100         {

101             try {

102                 throw new Exception();

103             } catch (Exception e) {

104                 e.printStackTrace();

105             }

106         }

107     }

108     public int size()

109     {

110         return size;

111     }

112     public static void main(String[] args)

113     {

114         mylinkedlist list=new mylinkedlist();

115         list.add("aaa");

116         list.add("bbb");

117         list.add("ccc");

118         list.add("ddd");

119         System.out.println(list.size());

120         System.out.println(list.get(1));

121         list.removefirst();

122         System.out.println(list.get(0));

123     }

124 }

125

126

127 class Node

128 {

129     private Node previous;

130     private Object obj;

131     private Node next;

132     public Node()

133     {

134     }

135     public Node(Node previous, Object obj, Node next) {

136         super();

137         this.previous = previous;

138         this.obj = obj;

139         this.next = next;

140     }

141     public Node getPrevious() {

142         return previous;

143     }

144     public void setPrevious(Node previous) {

145         this.previous = previous;

146     }

147     public Object getObj() {

148         return obj;

149     }

150     public void setObj(Object obj) {

151         this.obj = obj;

152     }

153     public Node getNext() {

154         return next;

155     }

156     public void setNext(Node next) {

157         this.next = next;

158     }

159 }

运行结果：

4
bbb
bbb