1. package ChapterFive;
2.
3. class DoubleLink<E> {
4.
5. public Link<E> first;
6.
7. public Link<E> last;
8.
9. int size;
10.
11. @SuppressWarnings("hiding")
12. class Link<E> {
13. public E data;
14.
15. public Link<E> next;// 链表的下一项
16.
17. public Link<E> previous;// 链表的前一项
18.
19. public Link(E value) {
20. this.data = value;
21. }
22. }
23.
24. public DoubleLink() {
25. first = null;
26. last = null;
27. size = 0;
28. }
29.
30. // 在链表的首部插入一项
31. public void insertFirst(E value) {
32. Link<E> newLink = new Link<E>(value);
33. if (isEmpty())// 如果链表为空则first == last
34. last = newLink;
35. else
36. first.previous = newLink;// 确定原first与newLink的前后关系
37. newLink.next = first;
38. first = newLink;// 设置新的first值
39. size++;
40. }
41.
42. // 在链表的尾部插入一项
43. public void insertLast(E value) {
44. Link<E> newLink = new Link<E>(value);
45. if (isEmpty())// 如果链表为空则last == first
46. first = newLink;
47. else {
48. last.next = newLink;// 确定原last与newLink的前后关系
49. newLink.previous = last;
50. }
51. last = newLink;// 设置新的last值
52. size++;
53. }
54.
55. // 删除双向链表的表头
56. public Link<E> deleteFirst() {
57. Link<E> temp = first;
58. if (first.next == null)// 链表中只有一项数据
59. last = null;
60. else
61. first.next.previous = null;// 销毁原链表的头部
62. first = first.next;
63. size--;
64. return temp;
65. }
66.
67. // 删除链表的最后一项
68. public Link<E> deleteLast() {
69. Link<E> temp = last;
70. if (first.next == null)// 链表中只有一项数据
71. first = null;
72. else
73. last.previous.next = null;// 销毁原链表的尾部
74. last = last.previous;
75. size--;
76. return temp;
77. }
78.
79. // 判断链表是否为空
80. public boolean isEmpty() {
81. return size == 0;
82. }
83.
84. // 输出链表中的所有数据项
85. public void display() {
86. Link<E> curr = first;
87. while (curr != null) {
88. System.out.print(curr.data + " ");
89. curr = curr.next;
90. }
91. System.out.println();
92. }
93. }
94.
95. public class DoubleLinkApp {
96. public static void main(String[] args) {
97. DoubleLink<Integer> dl = new DoubleLink<Integer>();
98. for (int i = 0; i < 5; i++) {
99. dl.insertFirst((int) (Math.random() * 100));
100. }
101. for (int i = 0; i < 5; i++) {
102. dl.insertLast((int) (Math.random() * 100));
103. }
104. dl.display();
105. while (!dl.isEmpty()) {
106. dl.deleteFirst();
107. dl.deleteLast();
108. dl.display();
109. }
110. System.out.println("Ok");
111. }
112. } |
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