From a526903f39f78ae91f5975755f79ecf647243f67 Mon Sep 17 00:00:00 2001 From: 1326670425 <1326670425@qq.com> Date: Fri, 19 Jul 2019 15:27:12 +0800 Subject: [PATCH] =?UTF-8?q?=E9=99=84=E5=BD=95=EF=BC=9A=E9=9B=86=E5=90=88?= =?UTF-8?q?=E4=B8=BB=E9=A2=98=20=E7=BF=BB=E8=AF=91=E6=9B=B4=E6=96=B0?= =?UTF-8?q?=E8=87=B3=E7=A4=BA=E4=BE=8B=E6=95=B0=E6=8D=AE?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- docs/book/Appendix-Collection-Topics.md | 353 ++++++++++++++++++++++++ 1 file changed, 353 insertions(+) diff --git a/docs/book/Appendix-Collection-Topics.md b/docs/book/Appendix-Collection-Topics.md index f479c55..f1b3dcc 100644 --- a/docs/book/Appendix-Collection-Topics.md +++ b/docs/book/Appendix-Collection-Topics.md @@ -3,10 +3,363 @@ # 附录:集合主题 +> 本附录是一些比[第十二章 集合]()中介绍的更高级的内容。 ## 示例数据 +这里创建一些样本数据用于集合示例。 以下数据将颜色名称与HTML颜色的RGB值相关联。请注意，每个键和值都是唯一的： + +```java +// onjava/HTMLColors.java +// Sample data for collection examples +package onjava; +import java.util.*; +import java.util.stream.*; +import java.util.concurrent.*; + +public class HTMLColors { + public static final Object[][] ARRAY = { + { 0xF0F8FF, "AliceBlue" }, + { 0xFAEBD7, "AntiqueWhite" }, + { 0x7FFFD4, "Aquamarine" }, + { 0xF0FFFF, "Azure" }, + { 0xF5F5DC, "Beige" }, + { 0xFFE4C4, "Bisque" }, + { 0x000000, "Black" }, + { 0xFFEBCD, "BlanchedAlmond" }, + { 0x0000FF, "Blue" }, + { 0x8A2BE2, "BlueViolet" }, + { 0xA52A2A, "Brown" }, + { 0xDEB887, "BurlyWood" }, + { 0x5F9EA0, "CadetBlue" }, + { 0x7FFF00, "Chartreuse" }, + { 0xD2691E, "Chocolate" }, + { 0xFF7F50, "Coral" }, + { 0x6495ED, "CornflowerBlue" }, + { 0xFFF8DC, "Cornsilk" }, + { 0xDC143C, "Crimson" }, + { 0x00FFFF, "Cyan" }, + { 0x00008B, "DarkBlue" }, + { 0x008B8B, "DarkCyan" }, + { 0xB8860B, "DarkGoldenRod" }, + { 0xA9A9A9, "DarkGray" }, + { 0x006400, "DarkGreen" }, + { 0xBDB76B, "DarkKhaki" }, + { 0x8B008B, "DarkMagenta" }, + { 0x556B2F, "DarkOliveGreen" }, + { 0xFF8C00, "DarkOrange" }, + { 0x9932CC, "DarkOrchid" }, + { 0x8B0000, "DarkRed" }, + { 0xE9967A, "DarkSalmon" }, + { 0x8FBC8F, "DarkSeaGreen" }, + { 0x483D8B, "DarkSlateBlue" }, + { 0x2F4F4F, "DarkSlateGray" }, + { 0x00CED1, "DarkTurquoise" }, + { 0x9400D3, "DarkViolet" }, + { 0xFF1493, "DeepPink" }, + { 0x00BFFF, "DeepSkyBlue" }, + { 0x696969, "DimGray" }, + { 0x1E90FF, "DodgerBlue" }, + { 0xB22222, "FireBrick" }, + { 0xFFFAF0, "FloralWhite" }, + { 0x228B22, "ForestGreen" }, + { 0xDCDCDC, "Gainsboro" }, + { 0xF8F8FF, "GhostWhite" }, + { 0xFFD700, "Gold" }, + { 0xDAA520, "GoldenRod" }, + { 0x808080, "Gray" }, + { 0x008000, "Green" }, + { 0xADFF2F, "GreenYellow" }, + { 0xF0FFF0, "HoneyDew" }, + { 0xFF69B4, "HotPink" }, + { 0xCD5C5C, "IndianRed" }, + { 0x4B0082, "Indigo" }, + { 0xFFFFF0, "Ivory" }, + { 0xF0E68C, "Khaki" }, + { 0xE6E6FA, "Lavender" }, + { 0xFFF0F5, "LavenderBlush" }, + { 0x7CFC00, "LawnGreen" }, + { 0xFFFACD, "LemonChiffon" }, + { 0xADD8E6, "LightBlue" }, + { 0xF08080, "LightCoral" }, + { 0xE0FFFF, "LightCyan" }, + { 0xFAFAD2, "LightGoldenRodYellow" }, + { 0xD3D3D3, "LightGray" }, + { 0x90EE90, "LightGreen" }, + { 0xFFB6C1, "LightPink" }, + { 0xFFA07A, "LightSalmon" }, + { 0x20B2AA, "LightSeaGreen" }, + { 0x87CEFA, "LightSkyBlue" }, + { 0x778899, "LightSlateGray" }, + { 0xB0C4DE, "LightSteelBlue" }, + { 0xFFFFE0, "LightYellow" }, + { 0x00FF00, "Lime" }, + { 0x32CD32, "LimeGreen" }, + { 0xFAF0E6, "Linen" }, + { 0xFF00FF, "Magenta" }, + { 0x800000, "Maroon" }, + { 0x66CDAA, "MediumAquaMarine" }, + { 0x0000CD, "MediumBlue" }, + { 0xBA55D3, "MediumOrchid" }, + { 0x9370DB, "MediumPurple" }, + { 0x3CB371, "MediumSeaGreen" }, + { 0x7B68EE, "MediumSlateBlue" }, + { 0x00FA9A, "MediumSpringGreen" }, + { 0x48D1CC, "MediumTurquoise" }, + { 0xC71585, "MediumVioletRed" }, + { 0x191970, "MidnightBlue" }, + { 0xF5FFFA, "MintCream" }, + { 0xFFE4E1, "MistyRose" }, + { 0xFFE4B5, "Moccasin" }, + { 0xFFDEAD, "NavajoWhite" }, + { 0x000080, "Navy" }, + { 0xFDF5E6, "OldLace" }, + { 0x808000, "Olive" }, + { 0x6B8E23, "OliveDrab" }, + { 0xFFA500, "Orange" }, + { 0xFF4500, "OrangeRed" }, + { 0xDA70D6, "Orchid" }, + { 0xEEE8AA, "PaleGoldenRod" }, + { 0x98FB98, "PaleGreen" }, + { 0xAFEEEE, "PaleTurquoise" }, + { 0xDB7093, "PaleVioletRed" }, + { 0xFFEFD5, "PapayaWhip" }, + { 0xFFDAB9, "PeachPuff" }, + { 0xCD853F, "Peru" }, + { 0xFFC0CB, "Pink" }, + { 0xDDA0DD, "Plum" }, + { 0xB0E0E6, "PowderBlue" }, + { 0x800080, "Purple" }, + { 0xFF0000, "Red" }, + { 0xBC8F8F, "RosyBrown" }, + { 0x4169E1, "RoyalBlue" }, + { 0x8B4513, "SaddleBrown" }, + { 0xFA8072, "Salmon" }, + { 0xF4A460, "SandyBrown" }, + { 0x2E8B57, "SeaGreen" }, + { 0xFFF5EE, "SeaShell" }, + { 0xA0522D, "Sienna" }, + { 0xC0C0C0, "Silver" }, + { 0x87CEEB, "SkyBlue" }, + { 0x6A5ACD, "SlateBlue" }, + { 0x708090, "SlateGray" }, + { 0xFFFAFA, "Snow" }, + { 0x00FF7F, "SpringGreen" }, + { 0x4682B4, "SteelBlue" }, + { 0xD2B48C, "Tan" }, + { 0x008080, "Teal" }, + { 0xD8BFD8, "Thistle" }, + { 0xFF6347, "Tomato" }, + { 0x40E0D0, "Turquoise" }, + { 0xEE82EE, "Violet" }, + { 0xF5DEB3, "Wheat" }, + { 0xFFFFFF, "White" }, + { 0xF5F5F5, "WhiteSmoke" }, + { 0xFFFF00, "Yellow" }, + { 0x9ACD32, "YellowGreen" }, + }; + public static final Map MAP = + Arrays.stream(ARRAY) + .collect(Collectors.toMap( + element -> (Integer)element[0], + element -> (String)element[1], + (v1, v2) -> { // Merge function + throw new IllegalStateException(); + }, + LinkedHashMap::new + )); + // Inversion only works if values are unique: + public static Map + invert(Map map) { + return map.entrySet().stream() + .collect(Collectors.toMap( + Map.Entry::getValue, + Map.Entry::getKey, + (v1, v2) -> { + throw new IllegalStateException(); + }, + LinkedHashMap::new + )); + } + public static final Map + INVMAP = invert(MAP); + // Look up RGB value given a name: + public static Integer rgb(String colorName) { + return INVMAP.get(colorName); + } + public static final List LIST = + Arrays.stream(ARRAY) + .map(item -> (String)item[1]) + .collect(Collectors.toList()); + public static final List RGBLIST = + Arrays.stream(ARRAY) + .map(item -> (Integer)item[0]) + .collect(Collectors.toList()); + public static + void show(Map.Entry e) { + System.out.format( + "0x%06X: %s%n", e.getKey(), e.getValue()); + } + public static void + show(Map m, int count) { + m.entrySet().stream() + .limit(count) + .forEach(e -> show(e)); + } + public static void show(Map m) { + show(m, m.size()); + } + public static + void show(Collection lst, int count) { + lst.stream() + .limit(count) + .forEach(System.out::println); + } + public static void show(Collection lst) { + show(lst, lst.size()); + } + public static + void showrgb(Collection lst, int count) { + lst.stream() + .limit(count) + .forEach(n -> System.out.format("0x%06X%n", n)); + } + public static void showrgb(Collection lst) { + showrgb(lst, lst.size()); + } + public static + void showInv(Map m, int count) { + m.entrySet().stream() + .limit(count) + .forEach(e -> + System.out.format( + "%-20s 0x%06X%n", e.getKey(), e.getValue())); + } + public static void showInv(Map m) { + showInv(m, m.size()); + } + public static void border() { + System.out.println( + "******************************"); + } +} +``` + +**MAP** 是使用Streams（[第十四章 流式编程]()）创建的。 二维数组 **ARRAY** 作为流传输到 **Map** 中，但请注意我们不仅仅是使用简单版本的 **Collectors.toMap()** 。 那个版本生成一个 **HashMap** ，它使用散列函数来控制对键的排序。 为了保留原来的顺序，我们必须将键值对直接放入 **TreeMap** 中，这意味着我们需要使用更复杂的 **Collectors.toMap()** 版本。这需要两个函数从每个流元素中提取键和值，就像简单版本的**Collectors.toMap()** 一样。 然后它需要一个*合并函数*（merge function），它解决了与同一个键相关的两个值之间的冲突。这里的数据已经预先审查过，因此绝不会发生这种情况，如果有的话，这里会抛出异常。最后，传递生成所需类型的空map的函数，然后用流来填充它。 + +**rgb()** 方法是一个便捷函数（convenience function），它接受颜色名称 **String** 参数并生成其数字RGB值。为此，我们需要一个反转版本的 **COLORS** ，它接受一个 **String**键并查找RGB的 **Integer** 值。 这是通过 **invert()** 方法实现的，如果任何 **COLORS** 值不唯一，则抛出异常。 + +我们还创建包含所有名称的 **LIST** ，以及包含十六进制表示法的RGB值的 **RGBLIST** 。 + +第一个 **show()** 方法接受一个 **Map.Entry** 并显示以十六进制表示的键，以便轻松地对原始 **ARRAY** 进行双重检查。 名称以 **show** 开头的每个方法都会重载两个版本，其中一个版本采用 **count** 参数来指示要显示的元素数量，第二个版本显示序列中的所有元素。 + +这里是一个基本的测试： + +```java +// collectiontopics/HTMLColorTest.java +import static onjava.HTMLColors.*; + +public class HTMLColorTest { + static final int DISPLAY_SIZE = 20; + public static void main(String[] args) { + show(MAP, DISPLAY_SIZE); + border(); + showInv(INVMAP, DISPLAY_SIZE); + border(); + show(LIST, DISPLAY_SIZE); + border(); + showrgb(RGBLIST, DISPLAY_SIZE); + } +} +/* Output: +0xF0F8FF: AliceBlue +0xFAEBD7: AntiqueWhite +0x7FFFD4: Aquamarine +0xF0FFFF: Azure +0xF5F5DC: Beige +0xFFE4C4: Bisque +0x000000: Black +0xFFEBCD: BlanchedAlmond +0x0000FF: Blue +0x8A2BE2: BlueViolet +0xA52A2A: Brown +0xDEB887: BurlyWood +0x5F9EA0: CadetBlue +0x7FFF00: Chartreuse +0xD2691E: Chocolate +0xFF7F50: Coral +0x6495ED: CornflowerBlue +0xFFF8DC: Cornsilk +0xDC143C: Crimson +0x00FFFF: Cyan +****************************** +AliceBlue 0xF0F8FF +AntiqueWhite 0xFAEBD7 +Aquamarine 0x7FFFD4 +Azure 0xF0FFFF +Beige 0xF5F5DC +Bisque 0xFFE4C4 +Black 0x000000 +BlanchedAlmond 0xFFEBCD +Blue 0x0000FF +BlueViolet 0x8A2BE2 +Brown 0xA52A2A +BurlyWood 0xDEB887 +CadetBlue 0x5F9EA0 +Chartreuse 0x7FFF00 +Chocolate 0xD2691E +Coral 0xFF7F50 +CornflowerBlue 0x6495ED +Cornsilk 0xFFF8DC +Crimson 0xDC143C +Cyan 0x00FFFF +****************************** +AliceBlue +AntiqueWhite +Aquamarine +Azure +Beige +Bisque +Black +BlanchedAlmond +Blue +BlueViolet +Brown +BurlyWood +CadetBlue +Chartreuse +Chocolate +Coral +CornflowerBlue +Cornsilk +Crimson +Cyan +****************************** +0xF0F8FF +0xFAEBD7 +0x7FFFD4 +0xF0FFFF +0xF5F5DC +0xFFE4C4 +0x000000 +0xFFEBCD +0x0000FF +0x8A2BE2 +0xA52A2A +0xDEB887 +0x5F9EA0 +0x7FFF00 +0xD2691E +0xFF7F50 +0x6495ED +0xFFF8DC +0xDC143C +0x00FFFF +*/ +``` + +可以看到，使用 **LinkedHashMap** 确实能够保留 **HTMLColors.ARRAY** 的顺序。 ## List表现