Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
Activator |
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| 2.0;2 |
1 | /** | |
2 | * Distribution License: | |
3 | * JSword is free software; you can redistribute it and/or modify it under | |
4 | * the terms of the GNU Lesser General Public License, version 2.1 or later | |
5 | * as published by the Free Software Foundation. This program is distributed | |
6 | * in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even | |
7 | * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | |
8 | * See the GNU Lesser General Public License for more details. | |
9 | * | |
10 | * The License is available on the internet at: | |
11 | * http://www.gnu.org/copyleft/lgpl.html | |
12 | * or by writing to: | |
13 | * Free Software Foundation, Inc. | |
14 | * 59 Temple Place - Suite 330 | |
15 | * Boston, MA 02111-1307, USA | |
16 | * | |
17 | * © CrossWire Bible Society, 2005 - 2016 | |
18 | * | |
19 | */ | |
20 | package org.crosswire.common.activate; | |
21 | ||
22 | import java.util.HashSet; | |
23 | import java.util.Set; | |
24 | ||
25 | /** | |
26 | * Manager for instances of Activatable. | |
27 | * | |
28 | * Activator should be used to manage all activate()ions and deactivate()ions so | |
29 | * that it can keep a track of exactly what is active and what can be | |
30 | * deactivated is save memory. | |
31 | * | |
32 | * @see gnu.lgpl.License The GNU Lesser General Public License for details. | |
33 | * @author Joe Walker | |
34 | */ | |
35 | public final class Activator { | |
36 | /** | |
37 | * Prevent instantiation | |
38 | */ | |
39 | 0 | private Activator() { |
40 | // singleton - no set-up needed | |
41 | 0 | } |
42 | ||
43 | /** | |
44 | * Check that a subject is activated and call activate() if not. | |
45 | * | |
46 | * @param subject | |
47 | * The thing to activate | |
48 | */ | |
49 | public static void activate(Activatable subject) { | |
50 | 0 | if (!activated.contains(subject) && subject != null) { |
51 | 0 | subject.activate(lock); |
52 | 0 | activated.add(subject); |
53 | } | |
54 | 0 | } |
55 | ||
56 | /** | |
57 | * If we need to tighten things up a bit we can save memory with this | |
58 | * | |
59 | * @param amount the amount by which to to reduce memory | |
60 | */ | |
61 | public static void reduceMemoryUsage(Kill amount) { | |
62 | 0 | amount.reduceMemoryUsage(); |
63 | 0 | } |
64 | ||
65 | /** | |
66 | * Deactivate an Activatable object. It is safe to activate() something and | |
67 | * then forget to deactivate() it since we keep a track of activated objects | |
68 | * and will automatically deactivate() when needed, so this method should | |
69 | * only be used when we are sure that something will not be needed again. | |
70 | * | |
71 | * @param subject | |
72 | * The thing to deactivate | |
73 | */ | |
74 | public static void deactivate(Activatable subject) { | |
75 | 0 | if (activated.contains(subject) && subject != null) { |
76 | 0 | subject.deactivate(lock); |
77 | 0 | activated.remove(subject); |
78 | } | |
79 | 0 | } |
80 | ||
81 | public static void deactivateAll() { | |
82 | 0 | for (Activatable item : activated) { |
83 | 0 | deactivate(item); |
84 | } | |
85 | 0 | } |
86 | ||
87 | /** | |
88 | * The list of things that we have activated | |
89 | */ | |
90 | 0 | private static Set<Activatable> activated = new HashSet<Activatable>(); |
91 | ||
92 | /** | |
93 | * The object we use to prevent others from | |
94 | */ | |
95 | 0 | private static Lock lock = new Lock(); |
96 | } |