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1
21 package com.db4o;
22
23 import java.util.*;
24
25
32 class P2ListElementIterator implements Iterator {
33
34 private final P2LinkedList i_list;
35
36 private P1ListElement i_preprevious;
37 private P1ListElement i_previous;
38 private P1ListElement i_next;
39
40 P2ListElementIterator(P2LinkedList a_list, P1ListElement a_next) {
41 i_list = a_list;
42 i_next = a_next;
43 checkNextActive();
44 }
45
46 private void checkNextActive() {
47 if (i_next != null) {
48 i_next.checkActive();
49 }
50 }
51
52 public void remove() {
53 if (i_previous != null) {
54 synchronized (i_previous.streamLock()) {
55 if (i_preprevious != null) {
56 i_preprevious.i_next = i_previous.i_next;
57 i_preprevious.update();
58 }
59 i_list.checkRemoved(i_preprevious, i_previous);
60 i_previous.delete(i_list.i_deleteRemoved);
61 }
62 }
63 }
64
65 public boolean hasNext() {
66 return i_next != null;
67 }
68
69 public Object  next() {
70 if (i_next != null) {
71 synchronized (i_next.streamLock()) {
72 i_preprevious = i_previous;
73 i_previous = i_next;
74 Object obj = i_next.activatedObject(i_list.elementActivationDepth());
75 i_next = i_next.i_next;
76 checkNextActive();
77 return obj;
78 }
79 }
80 return null;
81 }
82
83 P1ListElement nextElement() {
84 i_preprevious = i_previous;
85 i_previous = i_next;
86 i_next = i_next.i_next;
87 checkNextActive();
88 return i_previous;
89 }
90
91 P1ListElement move(int a_elements) {
92 if (a_elements < 0) {
93 return null;
94 }
95 for (int i = 0; i < a_elements; i++) {
96 if (hasNext()) {
97 nextElement();
98 } else {
99 return null;
100 }
101 }
102 if (hasNext()) {
103 return nextElement();
104 }
105 return null;
106 }
107
108 }
109
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Java API By Example, From Geeks To Geeks.