forked from lfkdsk/PracticeCode
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathMyLinkedList.java
More file actions
215 lines (149 loc) · 4.42 KB
/
MyLinkedList.java
File metadata and controls
215 lines (149 loc) · 4.42 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* Created by liufengkai on 16/7/9.
*/
public class MyLinkedList<AnyType> implements Iterator<AnyType> {
private static class Node<AnyType> {
public AnyType data;
public Node<AnyType> prev;
public Node<AnyType> next;
public Node(AnyType data,
Node<AnyType> prev,
Node<AnyType> next) {
this.data = data;
this.prev = prev;
this.next = next;
}
}
private int theSize;
private int modCount;
private Node<AnyType> beginMarker;
private Node<AnyType> endMarker;
public MyLinkedList() {
clear();
}
public void clear() {
beginMarker = new Node<>(null, null, null);
endMarker = new Node<>(null, beginMarker, null);
beginMarker.next = endMarker;
theSize = 0;
modCount++;
}
public int size() {
return theSize;
}
public boolean isEmpty() {
return size() == 0;
}
public boolean add(AnyType newVal) {
add(size(), newVal);
return true;
}
public void add(int index, AnyType newVal) {
addBefore(getNode(index), newVal);
}
public AnyType get(int index) {
return getNode(index).data;
}
public AnyType set(int index, AnyType newVal) {
Node<AnyType> p = getNode(index);
AnyType oldVal = p.data;
p.data = newVal;
return oldVal;
}
public AnyType remove(int index) {
return remove(getNode(index));
}
private void addBefore(Node<AnyType> p, AnyType x) {
Node<AnyType> newNode = new Node<>(x, p.prev, p);
newNode.prev.next = newNode;
p.prev = newNode;
theSize++;
modCount++;
}
private AnyType remove(Node<AnyType> p) {
p.next.prev = p.prev;
p.prev.next = p.next;
theSize--;
modCount++;
return p.data;
}
private Node<AnyType> getNode(int index) {
Node<AnyType> p;
if (index < 0 || index > size()) {
throw new IndexOutOfBoundsException();
}
if (index < size() / 2) {
p = beginMarker.next;
for (int i = 0; i < index; i++) {
p = p.next;
}
} else {
p = endMarker;
for (int i = size(); i < index; i--) {
p = p.prev;
}
}
return p;
}
public Iterator<AnyType> iterator() {
return new LinkedListIterator();
}
private class LinkedListIterator implements Iterator<AnyType> {
private Node<AnyType> current = beginMarker.next;
private int expectedModCount = modCount;
private boolean okToRemove = false;
@Override
public boolean hasNext() {
return current != endMarker;
}
@Override
public AnyType next() {
// 这是在比较修改数 如果在使用迭代器的过程中修改了
// 就会被甩出错误
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
if (!hasNext()) {
throw new NoSuchElementException();
}
AnyType nextItem = current.data;
current = current.next;
// 在这里直接亲定了可以修改移除
okToRemove = true;
return nextItem;
}
@Override
public void remove() {
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
if (!okToRemove) {
throw new IllegalStateException();
}
MyLinkedList.this.remove(current.prev);
okToRemove = false;
expectedModCount++;
}
}
@Override
public boolean hasNext() {
return false;
}
@Override
public AnyType next() {
return null;
}
public static void main(String[] args) {
MyLinkedList<String> linkedList = new MyLinkedList<>();
for (int i = 0; i < 10; i++) {
linkedList.add("i = " + i);
}
Iterator<String> iterator = linkedList.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
}
}