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
|
/* Glazed Lists (c) 2003-2006 */
/* http://publicobject.com/glazedlists/ publicobject.com,*/
/* O'Dell Engineering Ltd.*/
package ca.odell.glazedlists;
import ca.odell.glazedlists.event.ListEvent;
import java.util.Comparator;
/**
* An {@link EventList} that shows the unique elements from its source
* {@link EventList} ordered by the frequency of their appearance.
*
* <p>This {@link EventList} supports all write operations.
*
* <p><strong><font color="#FF0000">Warning:</font></strong> This class
* breaks the contract required by {@link java.util.List}. See
* {@link EventList} for an example.
*
* <p><strong><font color="#FF0000">Warning:</font></strong> This class is
* thread ready but not thread safe. See {@link EventList} for an example
* of thread safe code.
*
* <p><table border="1" width="100%" cellpadding="3" cellspacing="0">
* <tr class="TableHeadingColor"><td colspan=2><font size="+2"><b>EventList Overview</b></font></td></tr>
* <tr><td class="TableSubHeadingColor"><b>Writable:</b></td><td>yes</td></tr>
* <tr><td class="TableSubHeadingColor"><b>Concurrency:</b></td><td>thread ready, not thread safe</td></tr>
* <tr><td class="TableSubHeadingColor"><b>Performance:</b></td><td>reads: O(log N), writes O(log N)</td></tr>
* <tr><td class="TableSubHeadingColor"><b>Memory:</b></td><td>196 bytes per element</td></tr>
* <tr><td class="TableSubHeadingColor"><b>Unit Tests:</b></td><td>N/A</td></tr>
* <tr><td class="TableSubHeadingColor"><b>Issues:</b></td><td>
* <a href="https://glazedlists.dev.java.net/issues/show_bug.cgi?id=104">104</a>
* </td></tr>
* </table>
*
* @author <a href="mailto:jesse@swank.ca">Jesse Wilson</a>
*/
public final class PopularityList<E> extends TransformedList<E, E> {
/** the list of distinct elements */
private UniqueList<E> uniqueList;
/**
* Creates a new {@link PopularityList} that provides frequency-ranking
* for the specified {@link EventList}. All elements of the source {@link EventList}
* must implement {@link Comparable}.
*/
public static <E extends Comparable<? super E>> PopularityList<E> create(EventList<E> source) {
return new PopularityList<E>(UniqueList.create(source));
}
/**
* Creates a new {@link PopularityList} that provides frequency-ranking
* for the specified {@link EventList}. All elements of the source {@link EventList}
* must implement {@link Comparable}.
* <p>Usage of factory method {@link #create(EventList)} is preferable.
*/
public PopularityList(EventList<E> source) {
this(new UniqueList<E>(source));
}
/**
* Creates a new {@link PopularityList} that provides frequency-ranking
* for the specified {@link EventList}.
*
* @param uniqueComparator {@link Comparator} used to determine equality
*/
public PopularityList(EventList<E> source, Comparator<E> uniqueComparator) {
this(new UniqueList<E>(source, uniqueComparator));
}
/**
* Private constructor is used as a Java-language hack to allow us to save
* a reference to the specified {@link UniqueList}.
*/
private PopularityList(UniqueList<E> uniqueList) {
super(new SortedList<E>(uniqueList, new PopularityComparator<E>(uniqueList)));
this.uniqueList = uniqueList;
// listen for changes to the source list
source.addListEventListener(this);
}
/** {@inheritDoc} */
@Override
protected boolean isWritable() {
return true;
}
/** {@inheritDoc} */
@Override
public void listChanged(ListEvent<E> listChanges) {
updates.forwardEvent(listChanges);
}
/** {@inheritDoc} */
@Override
public void dispose() {
SortedList sortedSource = (SortedList)source;
super.dispose();
sortedSource.dispose();
uniqueList.dispose();
}
/**
* Compares objects by their popularity.
*/
private static class PopularityComparator<E> implements Comparator<E> {
private UniqueList<E> target;
public PopularityComparator(UniqueList<E> target) {
this.target = target;
}
public int compare(E a, E b) {
int aCount = target.getCount(a);
int bCount = target.getCount(b);
return bCount - aCount;
}
}
}
|
