{"id":1389,"date":"2025-08-21T16:26:31","date_gmt":"2025-08-21T08:26:31","guid":{"rendered":"https:\/\/zero-zl.cn\/?p=1389"},"modified":"2025-08-21T22:21:17","modified_gmt":"2025-08-21T14:21:17","slug":"java%e9%9b%86%e5%90%88","status":"publish","type":"post","link":"https:\/\/zero-zl.cn\/index.php\/2025\/08\/21\/java%e9%9b%86%e5%90%88\/","title":{"rendered":"Java\u96c6\u5408"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\" id=\"_1\u3001\u4ec0\u4e48\u662f\u96c6\u5408\"><a href=\"#_1\u3001\u4ec0\u4e48\u662f\u96c6\u5408\">1\u3001\u4ec0\u4e48\u662f\u96c6\u5408\uff1f<\/a><\/h2>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/zero-zl.cn\/wp-content\/uploads\/2025\/08\/image-20210720152950384-f-3okwE2-1024x712.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"712\" data-original=\"https:\/\/zero-zl.cn\/wp-content\/uploads\/2025\/08\/image-20210720152950384-f-3okwE2-1024x712.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-1449\"  sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/div><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<ul class=\"wp-block-list\">\n<li>\u96c6\u5408\u5c31\u662f\u4e00\u4e2a\u653e\u6570\u636e\u7684\u5bb9\u5668\uff0c\u51c6\u786e\u7684\u8bf4\u662f\u653e\u6570\u636e\u5bf9\u8c61\u5f15\u7528\u7684\u5bb9\u5668<\/li>\n\n\n\n<li>\u96c6\u5408\u7c7b\u5b58\u653e\u7684\u90fd\u662f\u5bf9\u8c61\u7684\u5f15\u7528\uff0c\u800c\u4e0d\u662f\u5bf9\u8c61\u7684\u672c\u8eab<\/li>\n\n\n\n<li>\u96c6\u5408\u7c7b\u578b\u4e3b\u8981\u67093\u79cd\uff1aset(\u96c6\uff09\u3001list(\u5217\u8868\uff09\u548cmap(\u6620\u5c04)\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u96c6\u5408\u7684\u7279\u70b9\u4e3b\u8981\u6709\u5982\u4e0b\u4e24\u70b9\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u96c6\u5408\u7528\u4e8e\u5b58\u50a8\u5bf9\u8c61\u7684\u5bb9\u5668\uff0c\u5bf9\u8c61\u662f\u7528\u6765\u5c01\u88c5\u6570\u636e\uff0c\u5bf9\u8c61\u591a\u4e86\u4e5f\u9700\u8981\u5b58\u50a8\u96c6\u4e2d\u5f0f\u7ba1\u7406\u3002<\/li>\n\n\n\n<li>\u548c\u6570\u7ec4\u5bf9\u6bd4\u5bf9\u8c61\u7684\u5927\u5c0f\u4e0d\u786e\u5b9a\u3002\u56e0\u4e3a\u96c6\u5408\u662f\u53ef\u53d8\u957f\u5ea6\u7684\u3002\u6570\u7ec4\u9700\u8981\u63d0\u524d\u5b9a\u4e49\u5927\u5c0f<\/li>\n<\/ul>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_2\u3001\u5e38\u7528\u7684\u96c6\u5408\u7c7b\u6709\u54ea\u4e9b\"><a href=\"#_2\u3001\u5e38\u7528\u7684\u96c6\u5408\u7c7b\u6709\u54ea\u4e9b\">2\u3001\u5e38\u7528\u7684\u96c6\u5408\u7c7b\u6709\u54ea\u4e9b\uff1f<\/a><\/h2>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/zero-zl.cn\/wp-content\/uploads\/2025\/08\/image-20210715114222299-CzACIKrs-1024x301.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"301\" data-original=\"https:\/\/zero-zl.cn\/wp-content\/uploads\/2025\/08\/image-20210715114222299-CzACIKrs-1024x301.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-1450\"  sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Collection<\/strong>\u96c6\u5408\u4e3b\u8981\u6709<strong>List<\/strong>\u548c<strong>Set<\/strong>\u4e24\u5927\u63a5\u53e3\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>List<\/strong>\uff1a\u4e00\u4e2a\u6709\u5e8f\uff08\u5143\u7d20\u5b58\u5165\u96c6\u5408\u7684\u987a\u5e8f\u548c\u53d6\u51fa\u7684\u987a\u5e8f\u4e00\u81f4\uff09\u5bb9\u5668\uff0c\u5143\u7d20\u53ef\u4ee5\u91cd\u590d\uff0c\u53ef\u4ee5\u63d2\u5165\u591a\u4e2anull\u5143\u7d20\uff0c\u5143\u7d20\u90fd\u6709\u7d22\u5f15\u3002\u5e38\u7528\u7684\u5b9e\u73b0\u7c7b\u6709 ArrayList\u3001LinkedList \u548c Vector\u3002<\/li>\n\n\n\n<li><strong>Set<\/strong>\uff1a\u4e00\u4e2a\u65e0\u5e8f\uff08\u5b58\u5165\u548c\u53d6\u51fa\u987a\u5e8f\u6709\u53ef\u80fd\u4e0d\u4e00\u81f4\uff09\u5bb9\u5668\uff0c\u4e0d\u53ef\u4ee5\u5b58\u50a8\u91cd\u590d\u5143\u7d20\uff0c\u53ea\u5141\u8bb8\u5b58\u5165\u4e00\u4e2anull\u5143\u7d20\uff0c\u5fc5\u987b\u4fdd\u8bc1\u5143\u7d20\u552f\u4e00\u6027\u3002Set \u63a5\u53e3\u5e38\u7528\u5b9e\u73b0\u7c7b\u662f HashSet\u3001LinkedHashSet \u4ee5\u53caTreeSet\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Map<\/strong>\u662f\u4e00\u4e2a\u952e\u503c\u5bf9\u96c6\u5408\uff0c\u5b58\u50a8\u952e\u3001\u503c\u548c\u4e4b\u95f4\u7684\u6620\u5c04\u3002 Key\u65e0\u5e8f\uff0c\u552f\u4e00\uff1bvalue \u4e0d\u8981\u6c42\u6709\u5e8f\uff0c\u5141\u8bb8\u91cd\u590d\u3002Map\u6ca1\u6709\u7ee7\u627f\u4e8eCollection\u63a5\u53e3\uff0c\u4eceMap\u96c6\u5408\u4e2d\u68c0\u7d22\u5143\u7d20\u65f6\uff0c\u53ea\u8981\u7ed9\u51fa\u952e\u5bf9\u8c61\uff0c\u5c31\u4f1a\u8fd4\u56de\u5bf9\u5e94\u7684\u503c\u5bf9\u8c61\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Map \u7684\u5e38\u7528\u5b9e\u73b0\u7c7b\uff1aHashMap\u3001TreeMap\u3001HashTable\u3001LinkedHashMap\u3001ConcurrentHashMap<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_3\u3001\u5feb\u901f\u5931\u8d25-fail-fast-\u548c\u5b89\u5168\u5931\u8d25-fail-safe-\u7684\u533a\u522b\u662f\u4ec0\u4e48\"><a href=\"#_3\u3001\u5feb\u901f\u5931\u8d25-fail-fast-\u548c\u5b89\u5168\u5931\u8d25-fail-safe-\u7684\u533a\u522b\u662f\u4ec0\u4e48\">3\u3001\u5feb\u901f\u5931\u8d25(fail-fast)\u548c\u5b89\u5168\u5931\u8d25(fail-safe)\u7684\u533a\u522b\u662f\u4ec0\u4e48\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Iterator \u7684\u5b89\u5168\u5931\u8d25\u662f\u57fa\u4e8e\u5bf9\u5e95\u5c42\u96c6\u5408\u505a\u62f7\u8d1d<\/strong>\uff0c\u56e0\u6b64\uff0c\u5b83\u4e0d\u53d7\u6e90\u96c6\u5408\u4e0a\u4fee\u6539\u7684\u5f71\u54cd\u3002java.util\u5305\u4e0b\u9762\u7684\u6240\u6709\u7684\u96c6\u5408\u7c7b\u90fd\u662f\u5feb\u901f\u5931\u8d25\u7684\uff0c\u800c java.util.concurrent \u5305\u4e0b\u9762\u7684\u6240\u6709\u7684\u7c7b\u90fd\u662f\u5b89\u5168\u5931\u8d25\u7684\u3002\u5feb\u901f\u5931\u8d25\u7684\u8fed\u4ee3\u5668\u4f1a\u629b\u51fa ConcurrentModificationException \u5f02\u5e38\uff0c\u800c\u5b89\u5168\u5931\u8d25\u7684\u8fed\u4ee3\u5668\u6c38\u8fdc\u4e0d\u4f1a\u629b\u51fa\u8fd9\u6837\u7684\u5f02\u5e38\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_4\u3001\u8fed\u4ee3\u5668iterator\u662f\u4ec0\u4e48\"><a href=\"#_4\u3001\u8fed\u4ee3\u5668iterator\u662f\u4ec0\u4e48\">4\u3001\u8fed\u4ee3\u5668Iterator\u662f\u4ec0\u4e48\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">Iterator \u63a5\u53e3\u63d0\u4f9b\u904d\u5386\u4efb\u4f55 Collection \u7684\u63a5\u53e3\u3002\u6211\u4eec\u53ef\u4ee5\u4ece\u4e00\u4e2a Collection \u4e2d\u4f7f\u7528\u8fed\u4ee3\u5668\u65b9\u6cd5\u6765\u83b7\u53d6\u8fed\u4ee3\u5668\u5b9e\u4f8b\u3002\u8fed\u4ee3\u5668\u53d6\u4ee3\u4e86 Java \u96c6\u5408\u6846\u67b6\u4e2d\u7684 Enumeration\uff0c\u8fed\u4ee3\u5668\u5141\u8bb8\u8c03\u7528\u8005\u5728\u8fed\u4ee3\u8fc7\u7a0b\u4e2d\u79fb\u9664\u5143\u7d20\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public interface Collection&lt;E&gt; extends Iterable&lt;E&gt; {\n ......\n}<\/code><\/pre>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_5\u3001iterator\u600e\u4e48\u4f7f\u7528-\u6709\u4ec0\u4e48\u7279\u70b9\"><a href=\"#_5\u3001iterator\u600e\u4e48\u4f7f\u7528-\u6709\u4ec0\u4e48\u7279\u70b9\">5\u3001Iterator\u600e\u4e48\u4f7f\u7528\uff1f\u6709\u4ec0\u4e48\u7279\u70b9\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u4f7f\u7528\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>List&lt;String&gt; list = new ArrayList&lt;&gt;(); \nIterator&lt;String&gt; it = list.iterator(); \nwhile(it.hasNext()){\n String obj = it.next(); \n System.out.println(obj); \n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Iterator \u7684\u7279\u70b9\u662f\u53ea\u80fd<strong>\u5355\u5411\u904d\u5386<\/strong>\uff0c\u4f46\u662f\u66f4\u52a0\u5b89\u5168\uff0c\u56e0\u4e3a\u5b83\u53ef\u4ee5\u786e\u4fdd\uff0c\u5728\u5f53\u524d\u904d\u5386\u7684\u96c6\u5408\u5143\u7d20\u88ab\u66f4\u6539\u7684\u65f6\u5019\uff0c\u5c31\u4f1a\u629b\u51fa ConcurrentModifificationException \u5f02\u5e38\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_6\u3001\u5982\u4f55\u8fb9\u904d\u5386\u8fb9\u79fb\u9664collection\u4e2d\u7684\u5143\u7d20\"><a href=\"#_6\u3001\u5982\u4f55\u8fb9\u904d\u5386\u8fb9\u79fb\u9664collection\u4e2d\u7684\u5143\u7d20\">6\u3001\u5982\u4f55\u8fb9\u904d\u5386\u8fb9\u79fb\u9664Collection\u4e2d\u7684\u5143\u7d20\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u8fb9\u904d\u5386\u8fb9\u4fee\u6539 Collection \u7684\u552f\u4e00\u6b63\u786e\u65b9\u5f0f\u662f\u4f7f\u7528 Iterator.remove() \u65b9\u6cd5<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Iterator&lt;Integer&gt; it = list.iterator(); \nwhile(it.hasNext()){ \n *\/\/ do something* it.remove(); \n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u5e38\u89c1\u9519\u8bef\u4ee3\u7801<\/strong>\uff1a\u7528for\u5faa\u73af\u8fdb\u884c\u79fb\u9664<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>for(Integer i : list){ \n list.remove(i) \n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u89e3\u6790\uff1a\u8fd0\u884c\u4ee5\u4e0a\u9519\u8bef\u4ee3\u7801\u4f1a\u62a5 <strong>ConcurrentModifificationException<\/strong> <strong>\u5f02\u5e38<\/strong>\u3002\u8fd9\u662f\u56e0\u4e3a\u5f53\u4f7f\u7528foreach(for(Integer i : list)) \u8bed\u53e5\u65f6\uff0c\u4f1a\u81ea\u52a8\u751f\u6210\u4e00\u4e2aiterator \u6765\u904d\u5386\u8be5 list\uff0c\u4f46\u540c\u65f6\u8be5 list \u6b63\u5728\u88abIterator.remove() \u4fee\u6539\u3002Java \u4e00\u822c\u4e0d\u5141\u8bb8\u4e00\u4e2a\u7ebf\u7a0b\u5728\u904d\u5386 Collection \u65f6\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u4fee\u6539\u5b83\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_7\u3001-iterator\u548clistiterator\u6709\u4ec0\u4e48\u533a\u522b\"><a href=\"#_7\u3001-iterator\u548clistiterator\u6709\u4ec0\u4e48\u533a\u522b\">7\u3001 Iterator\u548cListIterator\u6709\u4ec0\u4e48\u533a\u522b\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<ul class=\"wp-block-list\">\n<li>Iterator \u53ef\u4ee5\u904d\u5386 Set \u548c List \u96c6\u5408\uff0c\u800c ListIterator \u53ea\u80fd\u904d\u5386 List\u3002<\/li>\n\n\n\n<li>Iterator \u53ea\u80fd\u5355\u5411\u904d\u5386\uff0c\u800c ListIterator \u53ef\u4ee5\u53cc\u5411\u904d\u5386\uff08\u5411\u524d\/\u540e\u904d\u5386\uff09\u3002<\/li>\n\n\n\n<li>ListIterator \u5b9e\u73b0 Iterator \u63a5\u53e3\uff0c\u7136\u540e\u6dfb\u52a0\u4e86\u4e00\u4e9b\u989d\u5916\u7684\u529f\u80fd\uff0c\u6bd4\u5982\u6dfb\u52a0\u4e00\u4e2a\u5143\u7d20\u3001\u66ff\u6362\u4e00\u4e2a\u5143\u7d20\u3001\u83b7\u53d6\u524d\u9762\u6216\u540e\u9762\u5143\u7d20\u7684\u7d22\u5f15\u4f4d\u7f6e\u3002<\/li>\n<\/ul>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_8\u3001-\u904d\u5386\u4e00\u4e2alist\u6709\u54ea\u4e9b\u4e0d\u540c\u7684\u65b9\u5f0f-\u6bcf\u79cd\u65b9\u6cd5\u7684\u5b9e\u73b0\u539f\u7406\u662f\u4ec0\u4e48-java\u4e2dlist\u904d\u5386\u7684\u6700\u4f73\u5b9e\u8df5\u662f\u4ec0\u4e48\"><a href=\"#_8\u3001-\u904d\u5386\u4e00\u4e2alist\u6709\u54ea\u4e9b\u4e0d\u540c\u7684\u65b9\u5f0f-\u6bcf\u79cd\u65b9\u6cd5\u7684\u5b9e\u73b0\u539f\u7406\u662f\u4ec0\u4e48-java\u4e2dlist\u904d\u5386\u7684\u6700\u4f73\u5b9e\u8df5\u662f\u4ec0\u4e48\">8\u3001 \u904d\u5386\u4e00\u4e2aList\u6709\u54ea\u4e9b\u4e0d\u540c\u7684\u65b9\u5f0f\uff1f\u6bcf\u79cd\u65b9\u6cd5\u7684\u5b9e\u73b0\u539f\u7406\u662f\u4ec0\u4e48\uff1fJava\u4e2dList\u904d\u5386\u7684\u6700\u4f73\u5b9e\u8df5\u662f\u4ec0\u4e48\uff1f<\/a><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u904d\u5386\u65b9\u5f0f\u4ee5\u53ca\u539f\u7406<\/strong>\uff1a<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<ol class=\"wp-block-list\">\n<li><strong>for\u5faa\u73af<\/strong>\uff1a\u57fa\u4e8e\u8ba1\u6570\u5668\u3002\u5728\u96c6\u5408\u5916\u90e8\u7ef4\u62a4\u4e00\u4e2a\u8ba1\u6570\u5668\uff0c\u7136\u540e\u4f9d\u6b21\u8bfb\u53d6\u6bcf\u4e00\u4e2a\u4f4d\u7f6e\u7684\u5143\u7d20\uff0c\u5f53\u8bfb\u53d6\u5230\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u540e\u505c\u6b62\u3002<\/li>\n\n\n\n<li><strong>\u8fed\u4ee3\u5668\u904d\u5386<\/strong>\uff1aIterator \u662f\u9762\u5411\u5bf9\u8c61\u7684\u4e00\u4e2a\u8bbe\u8ba1\u6a21\u5f0f\uff0c\u76ee\u7684\u662f\u5c4f\u853d\u4e0d\u540c\u6570\u636e\u96c6\u5408\u7684\u7279\u70b9\uff0c\u7edf\u4e00\u904d\u5386\u96c6\u5408\u7684\u63a5\u53e3\u3002Java \u5728 Collections \u4e2d\u652f\u6301\u4e86 Iterator \u6a21\u5f0f\u3002<\/li>\n\n\n\n<li><strong>foreach \u5faa\u73af<\/strong>\uff1aforeach \u5185\u90e8\u4e5f\u662f\u91c7\u7528\u4e86 Iterator \u7684\u65b9\u5f0f\u5b9e\u73b0\uff0c\u4f7f\u7528\u65f6\u4e0d\u9700\u8981\u663e\u5f0f\u58f0\u660eIterator \u6216\u8ba1\u6570\u5668\u3002\u4f18\u70b9\u662f\u4ee3\u7801\u7b80\u6d01\uff0c\u4e0d\u6613\u51fa\u9519\uff1b\u7f3a\u70b9\u662f\u53ea\u80fd\u505a\u7b80\u5355\u7684\u904d\u5386\uff0c\u4e0d\u80fd\u5728\u904d\u5386\u8fc7\u7a0b\u4e2d\u64cd\u4f5c\u6570\u636e\u96c6\u5408\uff0c\u4f8b\u5982\u5220\u9664\u3001\u66ff\u6362\u3002<\/li>\n<\/ol>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u6700\u4f73\u5b9e\u8df5\u65b9\u5f0f<\/strong>\uff1a<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">Java Collections \u6846\u67b6\u4e2d\u63d0\u4f9b\u4e86\u4e00\u4e2a RandomAccess \u63a5\u53e3\uff0c\u7528\u6765\u6807\u8bb0 List \u5b9e\u73b0\u662f\u5426\u652f\u6301 Random Access\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5982\u679c\u4e00\u4e2a\u6570\u636e\u96c6\u5408\u5b9e\u73b0\u4e86\u8be5\u63a5\u53e3\uff0c\u5c31\u610f\u5473\u7740\u5b83\u652f\u6301 Random Access\uff0c\u6309\u4f4d\u7f6e\u8bfb\u53d6\u5143\u7d20\u7684\u5e73\u5747\u65f6\u95f4\u590d\u6742\u5ea6\u4e3a O(1)\uff0c\u5982ArrayList\u3002<\/li>\n\n\n\n<li>\u5982\u679c\u6ca1\u6709\u5b9e\u73b0\u8be5\u63a5\u53e3\uff0c\u8868\u793a\u4e0d\u652f\u6301 Random Access\uff0c\u5982LinkedList\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u63a8\u8350\u7684\u505a\u6cd5\uff1a<strong>\u652f\u6301 Random Access \u7684\u5217\u8868\u53ef\u7528 for \u5faa\u73af\u904d\u5386\uff0c\u5426\u5219\u5efa\u8bae\u7528 Iterator \u6216foreach \u904d\u5386\u3002<\/strong><\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_9\u3001-arraylist\u7684\u4f18\u7f3a\u70b9\"><a href=\"#_9\u3001-arraylist\u7684\u4f18\u7f3a\u70b9\">9\u3001 ArrayList\u7684\u4f18\u7f3a\u70b9\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>\u4f18\u70b9<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>ArrayList \u5e95\u5c42\u4ee5\u6570\u7ec4\u5b9e\u73b0\uff0c\u662f\u4e00\u79cd\u968f\u673a\u8bbf\u95ee\u6a21\u5f0f\u3002ArrayList \u5b9e\u73b0\u4e86 RandomAccess \u63a5\u53e3\uff0c\u56e0\u6b64\u67e5\u627e\u7684\u65f6\u5019\u975e\u5e38\u5feb\u3002<\/li>\n\n\n\n<li>ArrayList \u5728\u987a\u5e8f\u6dfb\u52a0\u4e00\u4e2a\u5143\u7d20\u7684\u65f6\u5019\u975e\u5e38\u65b9\u4fbf\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u7f3a\u70b9<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5220\u9664\u5143\u7d20\u7684\u65f6\u5019\uff0c\u9700\u8981\u505a\u4e00\u6b21\u5143\u7d20\u590d\u5236\u64cd\u4f5c\u3002\u5982\u679c\u8981\u590d\u5236\u7684\u5143\u7d20\u5f88\u591a\uff0c\u90a3\u4e48\u5c31\u4f1a\u6bd4\u8f83\u8017\u8d39\u6027\u80fd\u3002<\/li>\n\n\n\n<li>\u63d2\u5165\u5143\u7d20\u7684\u65f6\u5019\uff0c\u4e5f\u9700\u8981\u505a\u4e00\u6b21\u5143\u7d20\u590d\u5236\u64cd\u4f5c\uff0c\u7f3a\u70b9\u540c\u4e0a\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>ArrayList \u6bd4\u8f83\u9002\u5408\u987a\u5e8f\u6dfb\u52a0\u3001\u968f\u673a\u8bbf\u95ee\u7684\u573a\u666f\u3002<\/strong><\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_10\u3001-list-\u7684\u4e09\u4e2a\u5b50\u7c7b\u7684\u7279\u70b9\"><a href=\"#_10\u3001-list-\u7684\u4e09\u4e2a\u5b50\u7c7b\u7684\u7279\u70b9\">10\u3001 List \u7684\u4e09\u4e2a\u5b50\u7c7b\u7684\u7279\u70b9\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>ArrayList<\/strong>\uff1a\u5e95\u5c42\u7ed3\u6784\u662f\u6570\u7ec4\uff0c\u975e\u7ebf\u7a0b\u5b89\u5168\uff0c\u5e95\u5c42\u67e5\u8be2\u5feb\uff0c\u589e\u5220\u6162\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>LinkedList<\/strong>\uff1a\u5e95\u5c42\u7ed3\u6784\u662f\u94fe\u8868\u578b\u7684\uff0c\u975e\u7ebf\u7a0b\u5b89\u5168\uff0c\u589e\u5220\u5feb\uff0c\u67e5\u8be2\u6162\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>vector<\/strong>\uff1a\u5e95\u5c42\u7ed3\u6784\u662f\u6570\u7ec4\uff0c\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u589e\u5220\u6162\uff0c\u67e5\u8be2\u6162\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_11\u3001\u5982\u4f55\u5b9e\u73b0\u6570\u7ec4\u548clist\u4e4b\u95f4\u7684\u8f6c\u6362\"><a href=\"#_11\u3001\u5982\u4f55\u5b9e\u73b0\u6570\u7ec4\u548clist\u4e4b\u95f4\u7684\u8f6c\u6362\">11\u3001\u5982\u4f55\u5b9e\u73b0\u6570\u7ec4\u548cList\u4e4b\u95f4\u7684\u8f6c\u6362\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<ul class=\"wp-block-list\">\n<li>\u6570\u7ec4\u8f6cList\uff1a\u4f7f\u7528Arrays.asList(array)\u8fdb\u884c\u8f6c\u6362<\/li>\n\n\n\n<li>List\u8f6c\u6570\u7ec4\uff1a\u4f7f\u7528List\u81ea\u5e26\u7684toArray()\u65b9\u6cd5<code>\/\/ list to array List&lt;String&gt; list = new ArrayList&lt;String&gt;(); list.add(\"123\"); list.add(\"456\"); list.toArray(); \/\/ array to list String[] array = new String[]{\"123\",\"456\"}; Arrays.asList(array);<\/code><\/li>\n<\/ul>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_12\u3001java-\u4e2d-arraylist-\u548c-linkedlist-\u533a\u522b\"><a href=\"#_12\u3001java-\u4e2d-arraylist-\u548c-linkedlist-\u533a\u522b\">12\u3001Java \u4e2d ArrayList \u548c Linkedlist \u533a\u522b\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">ArrayList \u548c Vector \u4f7f\u7528\u4e86\u6570\u7ec4\u7684\u5b9e\u73b0\uff0c\u53ef\u4ee5\u8ba4\u4e3a ArrayList \u6216\u8005 Vector \u5c01\u88c5\u4e86\u5bf9\u5185\u90e8\u6570\u7ec4\u7684\u64cd\u4f5c\uff0c\u6bd4\u5982\u5411\u6570\u7ec4\u4e2d\u6dfb\u52a0\uff0c\u5220\u9664\uff0c\u63d2\u5165\u65b0\u7684\u5143\u7d20\u6216\u8005\u6570\u636e\u7684\u6269\u5c55\u548c\u91cd\u5b9a\u5411\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ArrayList \u662f\u57fa\u4e8e\u7d22\u5f15\u7684\u6570\u636e\u63a5\u53e3\uff0c\u5b83\u7684\u5e95\u5c42\u662f\u6570\u7ec4\u3002\u5b83\u53ef\u4ee5\u4ee5 <strong>O(1)\u65f6\u95f4\u590d\u6742\u5ea6\u5bf9\u5143\u7d20\u8fdb\u884c\u968f\u673a\u8bbf\u95ee<\/strong>\u3002\u4e0e\u6b64\u5bf9\u5e94\uff0cLinkedList \u662f\u4ee5\u5143\u7d20\u5217\u8868\u7684\u5f62\u5f0f\u5b58\u50a8\u5b83\u7684\u6570\u636e\uff0c\u6bcf\u4e00\u4e2a\u5143\u7d20\u90fd\u548c\u5b83\u7684\u524d\u4e00\u4e2a\u548c\u540e\u4e00\u4e2a\u5143\u7d20\u94fe\u63a5\u5728\u4e00\u8d77\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u67e5\u627e\u67d0\u4e2a\u5143\u7d20\u7684\u65f6\u95f4\u590d\u6742\u5ea6\u662f <strong>O(n)<\/strong>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u76f8\u5bf9\u4e8e ArrayList\uff0cLinkedList \u7684\u63d2\u5165\uff0c\u6dfb\u52a0\uff0c\u5220\u9664\u64cd\u4f5c\u901f\u5ea6\u66f4\u5feb\uff0c\u56e0\u4e3a\u5f53\u5143\u7d20\u88ab\u6dfb\u52a0\u5230\u96c6\u5408\u4efb\u610f\u4f4d\u7f6e\u7684\u65f6\u5019\uff0c\u4e0d\u9700\u8981\u50cf\u6570\u7ec4\u90a3\u6837\u91cd\u65b0\u8ba1\u7b97\u5927\u5c0f\u6216\u8005\u662f\u66f4\u65b0\u7d22\u5f15\u3002LinkedList \u6bd4 ArrayList \u66f4\u5360\u5185\u5b58\uff0c\u56e0\u4e3a LinkedList \u4e3a\u6bcf\u4e00\u4e2a\u8282\u70b9\u5b58\u50a8\u4e86\u4e24\u4e2a\u5f15\u7528\uff0c\u4e00\u4e2a\u6307\u5411\u524d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e00\u4e2a\u5143\u7d20\uff0c\u4e00\u4e2a\u6307\u5411\u4e0b\u4e00\u4e2a\u5143\u7d20\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_13\u3001list-a-new-arraylist-\u548c-arraylist-a-new-arraylist-\u7684\u533a\u522b\"><a href=\"#_13\u3001list-a-new-arraylist-\u548c-arraylist-a-new-arraylist-\u7684\u533a\u522b\">13\u3001List a=new ArrayList()\u548c ArrayList a =new ArrayList()\u7684\u533a\u522b\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<pre class=\"wp-block-code\"><code>List list = new ArrayList();<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u53e5\u8bdd\u521b\u5efa\u4e86\u4e00\u4e2aArrayList\u7684\u5bf9\u8c61\uff0c\u7136\u540e\u4e0a\u6eaf\u5230\u4e86List\uff0c\u6b64\u65f6list\u5df2\u7ecf\u662fList\u5bf9\u8c61\u4e86\uff0c\u6709\u4e9bArrayList\u6709\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\uff0c\u800cList\u6ca1\u6709\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\uff0clist\u5c31\u4e0d\u80fd\u518d\u4f7f\u7528\u4e86\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>ArrayList list=new ArrayList();<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u521b\u5efa\u4e00\u5bf9\u8c61\u5219\u4fdd\u7559\u4e86ArrayList \u7684\u6240\u6709\u5c5e\u6027\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f8b\u5982\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>List list = new ArrayList();\nArrayList arrayList = new ArrayList();\nlist.trimToSize(); \/\/\u9519\u8bef\uff0c\u6ca1\u6709\u8be5\u65b9\u6cd5\u3002\narrayList.trimToSize(); \/\/ArrayList \u91cc\u6709\u8be5\u65b9\u6cd5\u3002<\/code><\/pre>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_14\u3001\u591a\u7ebf\u7a0b\u573a\u666f\u4e0b\u5982\u4f55\u4f7f\u7528arraylist\"><a href=\"#_14\u3001\u591a\u7ebf\u7a0b\u573a\u666f\u4e0b\u5982\u4f55\u4f7f\u7528arraylist\">14\u3001\u591a\u7ebf\u7a0b\u573a\u666f\u4e0b\u5982\u4f55\u4f7f\u7528ArrayList\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">ArrayList\u4e0d\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u5982\u82e5\u9047\u5230\u591a\u7ebf\u7a0b\u573a\u666f\uff0c\u53ef\u4ee5\u901a\u8fc7 Collections \u7684 synchronizedList \u65b9\u6cd5\u5c06\u5176\u8f6c\u6362\u6210\u7ebf\u7a0b\u5b89\u5168\u7684\u5bb9\u5668\u540e\u518d\u4f7f\u7528\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>List&lt;String&gt; synchronizedList = Collections.synchronizedList(list);\nsynchronizedList.add(\"aaa\"); \nsynchronizedList.add(\"bbb\"); \nfor (int i = 0; i &lt; synchronizedList.size(); i++)\n{ \n System.out.println(synchronizedList.get(i)); \n}<\/code><\/pre>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_15\u3001list\u4e0eset\u7684\u533a\u522b\"><a href=\"#_15\u3001list\u4e0eset\u7684\u533a\u522b\">15\u3001List\u4e0eSet\u7684\u533a\u522b<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">List \uff0c Set \u90fd\u662f\u7ee7\u627f\u81eaCollection \u63a5\u53e3<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>List \u7279\u70b9<\/strong>\uff1a\u4e00\u4e2a\u6709\u5e8f\uff08\u5143\u7d20\u5b58\u5165\u96c6\u5408\u7684\u987a\u5e8f\u548c\u53d6\u51fa\u7684\u987a\u5e8f\u4e00\u81f4\uff09\u5bb9\u5668\uff0c\u5143\u7d20\u53ef\u4ee5\u91cd\u590d\uff0c\u53ef\u4ee5\u63d2\u5165\u591a\u4e2anull\u5143\u7d20\uff0c\u5143\u7d20\u90fd\u6709\u7d22\u5f15\u3002\u5e38\u7528\u7684\u5b9e\u73b0\u7c7b\u6709 ArrayList\u3001LinkedList \u548c Vector\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Set \u7279\u70b9<\/strong>\uff1a\u4e00\u4e2a\u65e0\u5e8f\uff08\u5b58\u5165\u548c\u53d6\u51fa\u987a\u5e8f\u6709\u53ef\u80fd\u4e0d\u4e00\u81f4\uff09\u5bb9\u5668\uff0c\u4e0d\u53ef\u4ee5\u5b58\u50a8\u91cd\u590d\u5143\u7d20\uff0c\u53ea\u5141\u8bb8\u5b58\u5165\u4e00\u4e2anull\u5143\u7d20\uff0c\u5fc5\u987b\u4fdd\u8bc1\u5143\u7d20\u552f\u4e00\u6027\u3002Set \u63a5\u53e3\u5e38\u7528\u5b9e\u73b0\u7c7b\u662f HashSet\u3001LinkedHashSet \u4ee5\u53caTreeSet\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u53e6\u5916 List \u652f\u6301for\u5faa\u73af\uff0c\u4e5f\u5c31\u662f\u901a\u8fc7\u4e0b\u6807\u6765\u904d\u5386\uff0c\u4e5f\u53ef\u4ee5\u7528\u8fed\u4ee3\u5668\uff0c\u4f46\u662fset\u53ea\u80fd\u7528\u8fed\u4ee3\uff0c\u56e0\u4e3a\u4ed6\u65e0\u5e8f\uff0c\u65e0\u6cd5\u7528\u4e0b\u6807\u6765\u53d6\u5f97\u60f3\u8981\u7684\u503c\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Set\u548cList\u5bf9\u6bd4<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Set\uff1a\u68c0\u7d22\u5143\u7d20\u6548\u7387\u4f4e\u4e0b\uff0c\u5220\u9664\u548c\u63d2\u5165\u6548\u7387\u9ad8\uff0c\u63d2\u5165\u548c\u5220\u9664\u4e0d\u4f1a\u5f15\u8d77\u5143\u7d20\u4f4d\u7f6e\u6539\u53d8\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">List\uff1a\u548c\u6570\u7ec4\u7c7b\u4f3c\uff0cList\u53ef\u4ee5\u52a8\u6001\u589e\u957f\uff0c\u67e5\u627e\u5143\u7d20\u6548\u7387\u9ad8\uff0c\u63d2\u5165\u5220\u9664\u5143\u7d20\u6548\u7387\u4f4e\uff0c\u56e0\u4e3a\u4f1a\u5f15\u8d77\u5176\u4ed6\u5143\u7d20\u4f4d\u7f6e\u6539\u53d8<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_16\u3001hashset\u7684\u5b9e\u73b0\u539f\u7406\"><a href=\"#_16\u3001hashset\u7684\u5b9e\u73b0\u539f\u7406\">16\u3001HashSet\u7684\u5b9e\u73b0\u539f\u7406\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">HashSet \u662f\u57fa\u4e8e HashMap \u5b9e\u73b0\u7684\uff0cHashSet\u7684\u503c\u5b58\u653e\u4e8eHashMap\u7684key\u4e0a\uff0cHashMap\u7684value\u7edf\u4e00\u4e3apresent\uff0c\u56e0\u6b64 HashSet \u7684\u5b9e\u73b0\u6bd4\u8f83\u7b80\u5355\uff0c\u76f8\u5173 HashSet \u7684\u64cd\u4f5c\uff0c\u57fa\u672c\u4e0a\u90fd\u662f\u76f4\u63a5\u8c03\u7528\u5e95\u5c42HashMap \u7684\u76f8\u5173\u65b9\u6cd5\u6765\u5b8c\u6210\uff0cHashSet \u4e0d\u5141\u8bb8\u91cd\u590d\u7684\u503c\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_17\u3001hash\u5982\u4f55\u68c0\u67e5\u91cd\u590d-\u5982\u4f55\u4fdd\u8bc1\u6570\u636e\u4e0d\u91cd\u590d\"><a href=\"#_17\u3001hash\u5982\u4f55\u68c0\u67e5\u91cd\u590d-\u5982\u4f55\u4fdd\u8bc1\u6570\u636e\u4e0d\u91cd\u590d\">17\u3001Hash\u5982\u4f55\u68c0\u67e5\u91cd\u590d\uff1f\u5982\u4f55\u4fdd\u8bc1\u6570\u636e\u4e0d\u91cd\u590d\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>\u68c0\u67e5\u91cd\u590d<\/strong>\uff1a\u5411HashSet \u4e2dadd ()\u5143\u7d20\u65f6\uff0c\u5224\u65ad\u5143\u7d20\u662f\u5426\u5b58\u5728\u7684\u4f9d\u636e\uff0c\u4e0d\u4ec5\u8981\u6bd4\u8f83hash\u503c\uff0c\u540c\u65f6\u8fd8\u8981\u7ed3\u5408equles \u65b9\u6cd5\u6bd4\u8f83\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">HashSet \u4e2d\u7684add ()\u65b9\u6cd5\u4f1a\u4f7f\u7528HashMap \u7684put()\u65b9\u6cd5\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u4fdd\u8bc1\u6570\u636e\u4e0d\u91cd\u590d<\/strong>\uff1aHashMap \u7684 key \u662f\u552f\u4e00\u7684\uff0c\u7531\u6e90\u7801\u53ef\u4ee5\u770b\u51fa HashSet \u6dfb\u52a0\u8fdb\u53bb\u7684\u503c\u5c31\u662f\u4f5c\u4e3aHashMap \u7684key\uff0c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5e76\u4e14\u5728HashMap\u4e2d\u5982\u679cK\/V\u76f8\u540c\u65f6\uff0c\u4f1a\u7528\u65b0\u7684V\u8986\u76d6\u6389\u65e7\u7684V\uff0c\u7136\u540e\u8fd4\u56de\u65e7\u7684V\u3002\u6240\u4ee5\u4e0d\u4f1a\u91cd\u590d\uff08HashMap \u6bd4\u8f83key\u662f\u5426\u76f8\u7b49\u662f\u5148\u6bd4\u8f83hashcode \u518d\u6bd4\u8f83equals \uff09\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">HashSet\u7684\u90e8\u5206\u6e90\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>private static final Object PRESENT = new Object(); \nprivate transient HashMap&lt;E,Object&gt; map; \npublic HashSet() { \n map = new HashMap&lt;&gt;(); \n}\npublic boolean add(E e) { \n \/\/ \u8c03\u7528HashMap\u7684put\u65b9\u6cd5,PRESENT\u662f\u4e00\u4e2a\u81f3\u59cb\u81f3\u7ec8\u90fd\u76f8\u540c\u7684\u865a\u503c \n return map.put(e, PRESENT)==null; \n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u6269\u5c55\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>hashCode\uff08\uff09\u4e0eequals\uff08\uff09\u7684\u76f8\u5173\u89c4\u5b9a<\/strong>\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5982\u679c\u4e24\u4e2a\u5bf9\u8c61\u76f8\u7b49\uff0c\u5219hashcode\u4e00\u5b9a\u4e5f\u662f\u76f8\u540c\u7684\uff0chashCode\u662fjdk\u6839\u636e\u5bf9\u8c61\u7684\u5730\u5740\u6216\u8005\u5b57\u7b26\u4e32\u6216\u8005\u6570\u5b57\u7b97\u51fa\u6765\u7684int\u7c7b\u578b\u7684\u6570\u503c<\/li>\n\n\n\n<li>\u4e24\u4e2a\u5bf9\u8c61\u76f8\u7b49\uff0c\u5bf9\u8c61\u4e24\u4e2aequals\u65b9\u6cd5\u8fd4\u56detrue<\/li>\n\n\n\n<li>\u4e24\u4e2a\u5bf9\u8c61\u6709\u76f8\u540c\u7684hashcode\u503c\uff0c\u5b83\u4eec\u4e5f\u4e0d\u4e00\u5b9a\u662f\u76f8\u7b49\u7684<\/li>\n\n\n\n<li>\u7efc\u4e0a\uff0cequals\u65b9\u6cd5\u88ab\u8986\u76d6\u8fc7\uff0c\u5219hashCode\u65b9\u6cd5\u4e5f\u5fc5\u987b\u88ab\u8986\u76d6<\/li>\n\n\n\n<li>hashCode()\u7684\u9ed8\u8ba4\u884c\u4e3a\u662f\u5bf9\u5806\u4e0a\u7684\u5bf9\u8c61\u4ea7\u751f\u72ec\u7279\u503c\u3002\u5982\u679c\u6ca1\u6709\u91cd\u5199hashCode()\uff0c\u5219\u8be5class\u7684\u4e24\u4e2a\u5bf9\u8c61\u65e0\u8bba\u5982\u4f55\u90fd\u4e0d\u4f1a\u76f8\u7b49\uff08\u5373\u4f7f\u8fd9\u4e24\u4e2a\u5bf9\u8c61\u6307\u5411\u76f8\u540c\u7684\u6570\u636e\uff09\u3002<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>==\u4e0eequals\u7684\u533a\u522b<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>==\u662f\u5224\u65ad\u4e24\u4e2a\u53d8\u91cf\u6216\u5b9e\u4f8b\u662f\u4e0d\u662f\u6307\u5411\u540c\u4e00\u4e2a\u5185\u5b58\u7a7a\u95f4 equals\u662f\u5224\u65ad\u4e24\u4e2a\u53d8\u91cf\u6216\u5b9e\u4f8b\u6240\u6307\u5411\u7684\u5185\u5b58\u7a7a\u95f4\u7684\u503c\u662f\u4e0d\u662f\u76f8\u540c<\/li>\n\n\n\n<li>==\u662f\u6307\u5bf9\u5185\u5b58\u5730\u5740\u8fdb\u884c\u6bd4\u8f83 equals()\u662f\u5bf9\u5b57\u7b26\u4e32\u7684\u5185\u5bb9\u8fdb\u884c\u6bd4\u8f83<\/li>\n<\/ol>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_18\u3001hashset\u4e0ehashmap\u7684\u533a\u522b\"><a href=\"#_18\u3001hashset\u4e0ehashmap\u7684\u533a\u522b\">18\u3001HashSet\u4e0eHashMap\u7684\u533a\u522b<\/a><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>HashSet<\/th><th>HashMap<\/th><\/tr><\/thead><tbody><tr><td>\u5b9e\u73b0Set\u63a5\u53e3<\/td><td>\u5b9e\u73b0Map\u63a5\u53e3<\/td><\/tr><tr><td>\u4ec5\u5b58\u50a8\u5bf9\u8c61<\/td><td>\u5b58\u50a8\u952e\u503c\u5bf9<\/td><\/tr><tr><td>\u8c03\u7528add()\u5411Set\u4e2d\u6dfb\u52a0\u5143\u7d20\uff0c<\/td><td>\u8c03\u7528put()\u5411Map\u4e2d\u6dfb\u52a0\u5143\u7d20<\/td><\/tr><tr><td>\u4f7f\u7528\u6210\u5458\u5bf9\u8c61\u8ba1\u7b97hashcode\u503c\uff0c\u5bf9\u4e8e\u4e24\u4e2a\u5bf9\u8c61\u6765\u8bf4\uff0chashcode\u53ef\u80fd\u76f8\u540c\uff0c\u6240\u4ee5equals()\u65b9\u6cd5\u7528\u6765\u5224\u65ad\u5bf9\u8c61\u7684\u76f8\u7b49\u6027<\/td><td>HashMap\u4f7f\u7528\u952e\uff08Key\uff09\u8ba1\u7b97<\/td><\/tr><tr><td>HashSet\u8f83HashMap\u6765\u8bf4\u6bd4\u8f83\u6162<\/td><td>HashMap\u76f8\u5bf9\u4e8eHashSet\u8f83\u5feb\uff0c\u56e0\u4e3a\u5b83\u4f7f\u7528\u552f\u4e00\u7684\u952e\u83b7\u53d6\u5bf9\u8c61<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_19\u3001\u4ec0\u4e48hash\u7b97\u6cd5\"><a href=\"#_19\u3001\u4ec0\u4e48hash\u7b97\u6cd5\">19\u3001\u4ec0\u4e48Hash\u7b97\u6cd5<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u54c8\u5e0c\u7b97\u6cd5\u662f\u6307\u628a\u4efb\u610f\u957f\u5ea6\u7684\u4e8c\u8fdb\u5236\u6620\u5c04\u4e3a\u56fa\u5b9a\u957f\u5ea6\u7684\u8f83\u5c0f\u7684\u4e8c\u8fdb\u5236\u503c\uff0c\u8fd9\u4e2a\u8f83\u5c0f\u7684\u4e8c\u8fdb\u5236\u503c\u53eb\u505a\u54c8\u5e0c\u503c\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_20\u3001hashmap\u7684\u5b9e\u73b0\u539f\u7406\"><a href=\"#_20\u3001hashmap\u7684\u5b9e\u73b0\u539f\u7406\">20\u3001HashMap\u7684\u5b9e\u73b0\u539f\u7406<\/a><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>HashMap\u6982\u8ff0<\/strong>\uff1aHashMap\u662f\u57fa\u4e8e\u54c8\u5e0c\u8868\u7684Map\u63a5\u53e3\u7684\u975e\u540c\u6b65\u5b9e\u73b0\u3002\u6b64\u5b9e\u73b0\u63d0\u4f9b\u6240\u6709\u53ef\u9009\u7684\u6620\u5c04\u64cd\u4f5c\uff0c\u5e76\u5141\u8bb8\u4f7f\u7528null\u503c\u548cnull\u952e\u3002\u6b64\u7c7b\u4e0d\u4fdd\u8bc1\u6620\u5c04\u7684\u987a\u5e8f\uff0c\u7279\u522b\u662f\u5b83\u4e0d\u4fdd\u8bc1\u8be5\u987a\u5e8f\u6052\u4e45\u4e0d\u53d8\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>HashMap\u7684\u6570\u636e\u7ed3\u6784<\/strong>\uff1a \u5728Java\u7f16\u7a0b\u8bed\u8a00\u4e2d\uff0c\u6700\u57fa\u672c\u7684\u7ed3\u6784\u5c31\u662f\u4e24\u79cd\uff0c\u4e00\u4e2a\u662f\u6570\u7ec4\uff0c\u53e6\u5916\u4e00\u4e2a\u662f\u6a21\u62df\u6307\u9488\uff08\u5f15\u7528\uff09\uff0c\u6240\u6709\u7684\u6570\u636e\u7ed3\u6784\u90fd\u53ef\u4ee5\u7528\u8fd9\u4e24\u4e2a\u57fa\u672c\u7ed3\u6784\u6765\u6784\u9020\u7684\uff0cHashMap\u4e5f\u4e0d\u4f8b\u5916\u3002HashMap\u5b9e\u9645\u4e0a\u662f\u4e00\u4e2a\u201c**\u94fe\u8868\u6563\u5217\u201d**\u7684\u6570\u636e\u7ed3\u6784\uff0c\u5373\u6570\u7ec4\u548c\u94fe\u8868\u7684\u7ed3\u5408\u4f53\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">HashMap \u57fa\u4e8e Hash \u7b97\u6cd5\u5b9e\u73b0\u7684<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5f53\u6211\u4eec\u5f80HashMap\u4e2dput\u5143\u7d20\u65f6\uff0c\u5229\u7528key\u7684hashCode\u91cd\u65b0hash\u8ba1\u7b97\u51fa\u5f53\u524d\u5bf9\u8c61\u7684\u5143\u7d20\u5728\u6570\u7ec4\u4e2d\u7684\u4e0b\u6807<\/li>\n\n\n\n<li>\u5b58\u50a8\u65f6\uff0c\u5982\u679c\u51fa\u73b0hash\u503c\u76f8\u540c\u7684key\uff0c\u6b64\u65f6\u6709\u4e24\u79cd\u60c5\u51b5\u3002\n<ul class=\"wp-block-list\">\n<li>\u5982\u679ckey\u76f8\u540c\uff0c\u5219\u8986\u76d6\u539f\u59cb\u503c\uff1b<\/li>\n\n\n\n<li>\u5982\u679ckey\u4e0d\u540c\uff08\u51fa\u73b0\u51b2\u7a81\uff09\uff0c\u5219\u5c06\u5f53\u524d\u7684key-value\u653e\u5165\u94fe\u8868\u4e2d<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>\u83b7\u53d6\u65f6\uff0c\u76f4\u63a5\u627e\u5230hash\u503c\u5bf9\u5e94\u7684\u4e0b\u6807\uff0c\u5728\u8fdb\u4e00\u6b65\u5224\u65adkey\u662f\u5426\u76f8\u540c\uff0c\u4ece\u800c\u627e\u5230\u5bf9\u5e94\u503c\u3002<\/li>\n\n\n\n<li>\u7406\u89e3\u4e86\u4ee5\u4e0a\u8fc7\u7a0b\u5c31\u4e0d\u96be\u660e\u767dHashMap\u662f\u5982\u4f55\u89e3\u51b3hash\u51b2\u7a81\u7684\u95ee\u9898\uff0c\u6838\u5fc3\u5c31\u662f\u4f7f\u7528\u4e86\u6570\u7ec4\u7684\u5b58\u50a8\u65b9\u5f0f\uff0c\u7136\u540e\u5c06\u51b2\u7a81\u7684key\u7684\u5bf9\u8c61\u653e\u5165\u94fe\u8868\u4e2d\uff0c\u4e00\u65e6\u53d1\u73b0\u51b2\u7a81\u5c31\u5728\u94fe\u8868\u4e2d\u505a\u8fdb\u4e00\u6b65\u7684\u5bf9\u6bd4\u3002<\/li>\n\n\n\n<li>\u9700\u8981\u6ce8\u610fJdk 1.8\u4e2d\u5bf9HashMap\u7684\u5b9e\u73b0\u505a\u4e86\u4f18\u5316\uff0c<strong>\u5f53\u94fe\u8868\u4e2d\u7684\u8282\u70b9\u6570\u636e\u8d85\u8fc7\u516b\u4e2a\u4e4b\u540e\uff0c\u8be5\u94fe\u8868\u4f1a\u8f6c\u4e3a\u7ea2\u9ed1\u6811\u6765\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\uff0c\u4ece\u539f\u6765\u7684O(n)\u5230O(logn)<\/strong><\/li>\n<\/ol>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_21\u3001hashmap\u5728jdk1-7\u4e0ejdk1-8\u4e2d\u6709\u54ea\u4e9b\u4e0d\u540c\"><a href=\"#_21\u3001hashmap\u5728jdk1-7\u4e0ejdk1-8\u4e2d\u6709\u54ea\u4e9b\u4e0d\u540c\">21\u3001HashMap\u5728JDK1.7\u4e0eJDK1.8\u4e2d\u6709\u54ea\u4e9b\u4e0d\u540c\uff1f<\/a><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u4e0d\u540c<\/th><th>JDK1.7<\/th><th>JDK1.8<\/th><\/tr><\/thead><tbody><tr><td>\u5b58\u50a8\u7ed3\u6784<\/td><td>\u6570\u7ec4+\u94fe\u8868<\/td><td>\u6570\u7ec4+\u94fe\u8868+\u7ea2\u9ed1\u6811<\/td><\/tr><tr><td>\u521d\u59cb\u5316\u65b9\u5f0f<\/td><td>\u5355\u72ec\u51fd\u6570\uff1a inflateTable()<\/td><td>\u76f4\u63a5\u96c6\u6210\u5230\u4e86\u6269\u5bb9\u51fd\u6570resize() \u4e2d<\/td><\/tr><tr><td>hash\u503c\u8ba1\u7b97\u65b9\u5f0f<\/td><td>\u6270\u52a8\u5904\u7406 = 9\u6b21\u6270\u52a8 = 4\u6b21\u4f4d\u8fd0\u7b97 + 5\u6b21\u5f02\u6216\u8fd0\u7b97<\/td><td>\u6270\u52a8\u5904\u7406 = 2\u6b21\u6270\u52a8 = 1\u6b21\u4f4d\u8fd0\u7b97 + 1\u6b21\u5f02\u6216\u8fd0\u7b97<\/td><\/tr><tr><td>\u5b58\u653e\u6570\u636e\u7684\u89c4\u5219<\/td><td>\u65e0\u51b2\u7a81\u65f6\uff0c\u5b58\u653e\u6570\u7ec4\uff1b\u51b2\u7a81\u65f6\uff0c\u5b58\u653e\u94fe\u8868<\/td><td>\u65e0\u51b2\u7a81\u65f6\uff0c\u5b58\u653e\u6570\u7ec4\uff1b\u51b2\u7a81 &amp; \u94fe\u8868\u957f\u5ea6 &lt;8\uff1a\u5b58\u653e\u5355\u94fe\u8868\uff1b\u51b2\u7a81 &amp; \u94fe\u8868\u957f\u5ea6 &gt; 8\uff1a\u6811\u5316\u5e76\u5b58\u653e\u7ea2\u9ed1\u6811<\/td><\/tr><tr><td>\u63d2\u5165\u6570\u636e\u65b9\u5f0f<\/td><td>\u5934\u63d2\u6cd5\uff08\u5148\u8bb2\u539f\u4f4d\u7f6e\u7684\u6570\u636e\u79fb\u5230\u540e1\u4f4d\uff0c\u518d\u63d2\u5165\u6570\u636e\u5230\u8be5\u4f4d\u7f6e\uff09<\/td><td>\u5c3e\u63d2\u6cd5\uff08\u76f4\u63a5\u63d2\u5165\u5230\u94fe\u8868\u5c3e\u90e8\/\u7ea2\u9ed1\u6811\uff09<\/td><\/tr><tr><td>\u6269\u5bb9\u540e\u5b58\u50a8\u4f4d\u7f6e\u7684\u8ba1\u7b97\u65b9\u5f0f<\/td><td>\u5168\u90e8\u6309\u7167\u539f\u6765\u65b9\u6cd5\u8fdb\u884c\u8ba1\u7b97\uff08\u5373hashCode -&gt;&gt; \u6270\u52a8\u51fd\u6570 -&gt;&gt; (h&amp;length-1)\uff09<\/td><td>\u6309\u7167\u6269\u5bb9\u540e\u7684\u89c4\u5f8b\u8ba1\u7b97\uff08\u5373\u6269\u5bb9\u540e\u7684\u4f4d\u7f6e=\u539f\u4f4d\u7f6e or \u539f\u4f4d\u7f6e + \u65e7\u5bb9\u91cf\uff09<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_22\u3001hashmap\u7684put\u65b9\u6cd5\u7684\u5177\u4f53\u6d41\u7a0b\"><a href=\"#_22\u3001hashmap\u7684put\u65b9\u6cd5\u7684\u5177\u4f53\u6d41\u7a0b\">22\u3001HashMap\u7684put\u65b9\u6cd5\u7684\u5177\u4f53\u6d41\u7a0b\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u5f53\u6211\u4eecput\u7684\u65f6\u5019\uff0c\u9996\u5148\u8ba1\u7b97 key \u7684hash \u503c\uff0c\u8fd9\u91cc\u8c03\u7528\u4e86 hash \u65b9\u6cd5\uff0c hash \u65b9\u6cd5\u5b9e\u9645\u662f\u8ba9key.hashCode() \u4e0ekey.hashCode()&gt;&gt;&gt;16 \u8fdb\u884c\u5f02\u6216\u64cd\u4f5c\uff0c\u9ad816bit\u88650\uff0c\u4e00\u4e2a\u6570\u548c0\u5f02\u6216\u4e0d\u53d8\uff0c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6240\u4ee5 hash \u51fd\u6570\u5927\u6982\u7684\u4f5c\u7528\u5c31\u662f\uff1a\u9ad816bit\u4e0d\u53d8\uff0c\u4f4e16bit\u548c\u9ad816bit\u505a\u4e86\u4e00\u4e2a\u5f02\u6216\uff0c\u76ee\u7684\u662f\u51cf\u5c11\u78b0\u649e\u3002\u6309\u7167\u51fd\u6570\u6ce8\u91ca\uff0c\u56e0\u4e3abucket\u6570\u7ec4\u5927\u5c0f\u662f2\u7684\u5e42\uff0c\u8ba1\u7b97\u4e0b\u6807index = (table.length &#8211; 1) &amp;hash \uff0c\u5982\u679c\u4e0d\u505a hash \u5904\u7406\uff0c\u76f8\u5f53\u4e8e\u6563\u5217\u751f\u6548\u7684\u53ea\u6709\u51e0\u4e2a\u4f4e bit \u4f4d\uff0c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3a\u4e86\u51cf\u5c11\u6563\u5217\u7684\u78b0\u649e\uff0c\u8bbe\u8ba1\u8005\u7efc\u5408\u8003\u8651\u4e86\u901f\u5ea6\u3001\u4f5c\u7528\u3001\u8d28\u91cf\u4e4b\u540e\uff0c\u4f7f\u7528\u9ad816bit\u548c\u4f4e16bit\u5f02\u6216\u6765\u7b80\u5355\u5904\u7406\u51cf\u5c11\u78b0\u649e\uff0c\u800c\u4e14JDK8\u4e2d<br>\u7528\u4e86\u590d\u6742\u5ea6 O\uff08logn\uff09\u7684\u6811\u7ed3\u6784\u6765\u63d0\u5347\u78b0\u649e\u4e0b\u7684\u6027\u80fd\u3002<\/p>\n<\/blockquote>\n\n\n\n<figure class=\"wp-block-image size-large\"><div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/zero-zl.cn\/wp-content\/uploads\/2025\/08\/image-20210716112216388-BGFm7B5B-1024x671.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"671\" data-original=\"https:\/\/zero-zl.cn\/wp-content\/uploads\/2025\/08\/image-20210716112216388-BGFm7B5B-1024x671.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" class=\"wp-image-1451\"  sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_23\u3001\u80fd\u5426\u4f7f\u7528\u4efb\u4f55\u7c7b\u4f5c\u4e3a-map-\u7684-key\"><a href=\"#_23\u3001\u80fd\u5426\u4f7f\u7528\u4efb\u4f55\u7c7b\u4f5c\u4e3a-map-\u7684-key\">23\u3001\u80fd\u5426\u4f7f\u7528\u4efb\u4f55\u7c7b\u4f5c\u4e3a Map \u7684 key\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u53ef\u4ee5\u4f7f\u7528\u4efb\u4f55\u7c7b\u4f5c\u4e3a Map \u7684 key\uff0c\u7136\u800c\u5728\u4f7f\u7528\u4e4b\u524d\uff0c\u9700\u8981\u8003\u8651\u4ee5\u4e0b\u51e0\u70b9\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5982\u679c\u7c7b\u91cd\u5199\u4e86 equals() \u65b9\u6cd5\uff0c\u4e5f\u5e94\u8be5\u91cd\u5199 hashCode() \u65b9\u6cd5\u3002<\/li>\n\n\n\n<li>\u7c7b\u7684\u6240\u6709\u5b9e\u4f8b\u9700\u8981\u9075\u5faa\u4e0e equals() \u548c hashCode() \u76f8\u5173\u7684\u89c4\u5219\u3002<\/li>\n\n\n\n<li>\u5982\u679c\u4e00\u4e2a\u7c7b\u6ca1\u6709\u4f7f\u7528 equals()\uff0c\u4e0d\u5e94\u8be5\u5728 hashCode() \u4e2d\u4f7f\u7528\u5b83\u3002<\/li>\n\n\n\n<li>\u7528\u6237\u81ea\u5b9a\u4e49 Key \u7c7b\u6700\u4f73\u5b9e\u8df5\u662f\u4f7f\u4e4b\u4e3a\u4e0d\u53ef\u53d8\u7684\uff0c\u8fd9\u6837 hashCode() \u503c\u53ef\u4ee5\u88ab\u7f13\u5b58\u8d77\u6765\uff0c\u62e5\u6709\u66f4\u597d\u7684\u6027\u80fd\u3002\u4e0d\u53ef\u53d8\u7684\u7c7b\u4e5f\u53ef\u4ee5\u786e\u4fdd hashCode() \u548c equals() \u5728\u672a\u6765\u4e0d\u4f1a\u6539\u53d8\uff0c\u8fd9\u6837\u5c31\u4f1a\u89e3\u51b3\u4e0e\u53ef\u53d8\u76f8\u5173\u7684\u95ee\u9898\u4e86\u3002<\/li>\n<\/ul>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_23\u3001\u4e3a\u4ec0\u4e48hashmap\u4e2dstring\u3001integer\u8fd9\u6837\u7684\u5305\u88c5\u7c7b\u9002\u5408\u4f5c\u4e3akey\"><a href=\"#_23\u3001\u4e3a\u4ec0\u4e48hashmap\u4e2dstring\u3001integer\u8fd9\u6837\u7684\u5305\u88c5\u7c7b\u9002\u5408\u4f5c\u4e3akey\">23\u3001\u4e3a\u4ec0\u4e48HashMap\u4e2dString\u3001Integer\u8fd9\u6837\u7684\u5305\u88c5\u7c7b\u9002\u5408\u4f5c\u4e3aKey\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">String\u3001Integer\u7b49\u5305\u88c5\u7c7b\u7684\u7279\u6027\u80fd\u591f\u4fdd\u8bc1hash\u503c\u7684\u4e0d\u53ef\u66f4\u6539\u6027\u548c\u8ba1\u7b97\u51c6\u786e\u6027\uff0c\u80fd\u591f\u6709\u6548\u8f83\u5c11hash\u7684\u78b0\u649e\u51e0\u7387\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u539f\u56e0\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u90fd\u662ffinal\u7c7b\u578b\uff0c\u5373\u4e0d\u53ef\u53d8\u6027\uff0c\u4fdd\u8bc1key\u7684\u4e0d\u53ef\u66f4\u6539\u6027\uff0c\u4e0d\u4f1a\u5b58\u5728\u83b7\u53d6hash\u503c\u4e0d\u540c\u7684\u60c5\u51b5\u3002<\/li>\n\n\n\n<li>\u5185\u90e8\u5df2\u91cd\u5199\u4e86equals() \u3001hashCode() \u7b49\u65b9\u6cd5\uff0c\u9075\u5b88\u4e86HashMap\u5185\u90e8\u7684\u89c4\u8303\uff08\u4e0d\u6e05\u695a\u53ef\u4ee5\u53bb\u4e0a\u9762\u770b\u770bputValue\u7684\u8fc7\u7a0b\uff09\uff0c\u4e0d\u5bb9\u6613\u51fa\u73b0Hash\u503c\u8ba1\u7b97\u9519\u8bef\u7684\u60c5\u51b5\uff1b<\/li>\n<\/ul>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_24\u3001\u5982\u679c\u4f7f\u7528object\u4f5c\u4e3ahashmap\u7684key-\u5e94\u8be5\u600e\u4e48\u529e\u5462\"><a href=\"#_24\u3001\u5982\u679c\u4f7f\u7528object\u4f5c\u4e3ahashmap\u7684key-\u5e94\u8be5\u600e\u4e48\u529e\u5462\">24\u3001\u5982\u679c\u4f7f\u7528Object\u4f5c\u4e3aHashMap\u7684Key\uff0c\u5e94\u8be5\u600e\u4e48\u529e\u5462\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>\u91cd\u5199hashCode() \u548cequals() \u65b9\u6cd5<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u91cd\u5199hashCode() \u662f\u56e0\u4e3a\u9700\u8981\u8ba1\u7b97\u5b58\u50a8\u6570\u636e\u7684\u5b58\u50a8\u4f4d\u7f6e\uff0c\u9700\u8981\u6ce8\u610f\u4e0d\u8981\u8bd5\u56fe\u4ece\u6563\u5217\u7801\u8ba1\u7b97\u4e2d<br>\u6392\u9664\u6389\u4e00\u4e2a\u5bf9\u8c61\u7684\u5173\u952e\u90e8\u5206\u6765\u63d0\u9ad8\u6027\u80fd\uff0c\u8fd9\u6837\u867d\u7136\u80fd\u66f4\u5feb\u4f46\u53ef\u80fd\u4f1a\u5bfc\u81f4\u66f4\u591a\u7684Hash\u78b0\u649e\uff1b<\/li>\n\n\n\n<li>\u91cd\u5199equals() \u65b9\u6cd5\uff0c\u9700\u8981\u9075\u5b88\u81ea\u53cd\u6027\u3001\u5bf9\u79f0\u6027\u3001\u4f20\u9012\u6027\u3001\u4e00\u81f4\u6027\u4ee5\u53ca\u5bf9\u4e8e\u4efb\u4f55\u975enull\u7684\u5f15\u7528<br>\u503cx\uff0cx.equals(null)\u5fc5\u987b\u8fd4\u56defalse\u7684\u8fd9\u51e0\u4e2a\u7279\u6027\uff0c\u76ee\u7684\u662f\u4e3a\u4e86\u4fdd\u8bc1key\u5728\u54c8\u5e0c\u8868\u4e2d\u7684\u552f\u4e00\u6027\uff1b<\/li>\n<\/ol>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_25\u3001hashmap-\u4e0e-hashtable-\u6709\u4ec0\u4e48\u533a\u522b\"><a href=\"#_25\u3001hashmap-\u4e0e-hashtable-\u6709\u4ec0\u4e48\u533a\u522b\">25\u3001HashMap \u4e0e HashTable \u6709\u4ec0\u4e48\u533a\u522b\uff1f<\/a><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u4e0d\u540c<\/th><th>HashMap<\/th><th>HashTable<\/th><\/tr><\/thead><tbody><tr><td>\u7ebf\u7a0b\u5b89\u5168<\/td><td>\u975e\u7ebf\u7a0b\u5b89\u5168<\/td><td>\u7ebf\u7a0b\u5b89\u5168\uff0c\u5185\u90e8\u901a\u8fc7<code>synchronized<\/code>\u4fee\u9970<\/td><\/tr><tr><td>\u6548\u7387<\/td><td>HashMap \u8981\u6bd4 HashTable \u6548\u7387\u9ad8\u4e00\u70b9<\/td><td>\u51e0\u4e4e\u4e0d\u4f7f\u7528\uff0c\u7ebf\u7a0b\u5b89\u5168\u4f7f\u7528<code>ConcurrentHashMap<\/code><\/td><\/tr><tr><td>\u5bf9Null key \u548cNull value\u7684\u652f\u6301<\/td><td>null\u4f5c\u4e3akey\uff0c\u6709\u4e14\u53ea\u6709\u4e00\u4e2a\uff0c\u4f46\u53ef\u4ee5\u5bf9\u5e94\u4e00\u4e2a\u6216\u591a\u4e2anull\u7684value<\/td><td>\u4e0d\u652f\u6301\uff0c\u53ea\u8981\u6709\uff0c\u5c31\u4f1a\u629b\u51fa<code>NullPointerException<\/code><\/td><\/tr><tr><td>\u521d\u59cb\u5bb9\u91cf\u5927\u5c0f\u548c\u6bcf\u6b21\u6269\u5145\u5bb9\u91cf\u5927\u5c0f\u7684\u4e0d\u540c**\uff1a\u521b\u5efa\u4e0d\u6307\u5b9a\u5bb9\u91cf**<\/td><td>\u521d\u59cb\u4e3a16\uff0c\u6bcf\u6b21\u6269\u5145\u53d8\u4e3a\u539f\u6765\u76842\u500d<\/td><td>\u521d\u59cb\u4e3a11\uff0c\u6269\u5145\u6bcf\u6b21\u53d8\u4e3a\u539f\u6765\u76842n+1<\/td><\/tr><tr><td>\u521d\u59cb\u5bb9\u91cf\u5927\u5c0f\u548c\u6bcf\u6b21\u6269\u5145\u5bb9\u91cf\u5927\u5c0f\u7684\u4e0d\u540c**\uff1a\u521b\u5efa\u6307\u5b9a\u5bb9\u91cf**<\/td><td>\u6269\u5145\u4e3a2\u7684\u5e42\u6b21\u65b9\u5927\u5c0f<\/td><td>\u6307\u5b9a\u5bb9\u91cf\u5927\u5c0f<\/td><\/tr><tr><td>\u5e95\u5c42\u6570\u636e\u7ed3\u6784<\/td><td>\u54c8\u5e0c\u8868\u7ed3\u6784<\/td><td>\u54c8\u5e0c\u8868\u7ed3\u6784<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_26\u3001\u5982\u4f55\u51b3\u5b9a\u4f7f\u7528-hashmap-\u8fd8\u662f-treemap\"><a href=\"#_26\u3001\u5982\u4f55\u51b3\u5b9a\u4f7f\u7528-hashmap-\u8fd8\u662f-treemap\">26\u3001\u5982\u4f55\u51b3\u5b9a\u4f7f\u7528 HashMap \u8fd8\u662f TreeMap\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u5bf9\u4e8e\u5728Map\u4e2d<strong>\u63d2\u5165\u3001\u5220\u9664\u548c\u5b9a\u4f4d<\/strong>\u5143\u7d20\u8fd9\u7c7b\u64cd\u4f5c\uff0c<strong>HashMap\u662f\u6700\u597d\u7684\u9009\u62e9<\/strong>\u3002\u7136\u800c\uff0c\u5047\u5982\u4f60\u9700\u8981\u5bf9\u4e00\u4e2a\u6709\u5e8f\u7684key\u96c6\u5408\u8fdb\u884c<strong>\u904d\u5386<\/strong>\uff0c<strong>TreeMap<\/strong>\u662f\u66f4\u597d\u7684\u9009\u62e9\u3002\u57fa\u4e8e\u4f60\u7684collection\u7684\u5927\u5c0f\uff0c\u4e5f\u8bb8\u5411HashMap\u4e2d\u6dfb\u52a0\u5143\u7d20\u4f1a\u66f4\u5feb\uff0c\u5c06map\u6362\u4e3aTreeMap\u8fdb\u884c\u6709\u5e8fkey\u7684\u904d\u5386\u3002<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_27\u3001hashmap-\u548c-concurrenthashmap-\u7684\u533a\u522b\"><a href=\"#_27\u3001hashmap-\u548c-concurrenthashmap-\u7684\u533a\u522b\">27\u3001HashMap \u548c ConcurrentHashMap \u7684\u533a\u522b\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<ol class=\"wp-block-list\">\n<li>ConcurrentHashMap\u5bf9\u6574\u4e2a\u6876\u6570\u7ec4\u8fdb\u884c\u4e86\u5206\u5272\u5206\u6bb5(Segment)\uff0c\u7136\u540e\u5728\u6bcf\u4e00\u4e2a<strong>\u5206\u6bb5\u4e0a\u90fd\u7528lock\u9501\u8fdb\u884c\u4fdd\u62a4<\/strong>\uff0c\u76f8\u5bf9\u4e8eHashTable\u7684synchronized\u9501\u7684\u7c92\u5ea6\u66f4\u7cbe\u7ec6\u4e86\u4e00\u4e9b\uff0c\u5e76\u53d1\u6027\u80fd\u66f4\u597d\uff0c\u800cHashMap\u6ca1\u6709\u9501\u673a\u5236\uff0c\u4e0d\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\u3002\uff08JDK1.8\u4e4b\u540eConcurrentHashMap\u542f\u7528\u4e86\u4e00\u79cd\u5168\u65b0\u7684\u65b9\u5f0f\u5b9e\u73b0,\u5229\u7528<strong>CAS\u7b97\u6cd5<\/strong>\u3002\uff09<\/li>\n\n\n\n<li>HashMap\u7684\u952e\u503c\u5bf9\u5141\u8bb8\u6709null\uff0c\u4f46\u662fConCurrentHashMap\u90fd\u4e0d\u5141\u8bb8\u3002<\/li>\n<\/ol>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"_28\u3001collection-\u548c-collections-\u6709\u4ec0\u4e48\u533a\u522b\"><a href=\"#_28\u3001collection-\u548c-collections-\u6709\u4ec0\u4e48\u533a\u522b\">28\u3001Collection \u548c Collections \u6709\u4ec0\u4e48\u533a\u522b\uff1f<\/a><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>java.util.Collection \u662f\u4e00\u4e2a\u96c6\u5408\u63a5\u53e3\uff08\u96c6\u5408\u7c7b\u7684\u4e00\u4e2a\u9876\u7ea7\u63a5\u53e3\uff09<\/strong>\u3002\u5b83\u63d0\u4f9b\u4e86\u5bf9\u96c6\u5408\u5bf9\u8c61\u8fdb\u884c\u57fa\u672c\u64cd\u4f5c\u7684\u901a\u7528\u63a5\u53e3\u65b9\u6cd5\u3002Collection\u63a5\u53e3\u5728Java \u7c7b\u5e93\u4e2d\u6709\u5f88\u591a\u5177\u4f53\u7684\u5b9e\u73b0\u3002Collection\u63a5\u53e3\u7684\u610f\u4e49\u662f\u4e3a\u5404\u79cd\u5177\u4f53\u7684\u96c6\u5408\u63d0\u4f9b\u4e86\u6700\u5927\u5316\u7684\u7edf\u4e00\u64cd\u4f5c\u65b9\u5f0f\uff0c\u5176\u76f4\u63a5\u7ee7\u627f\u63a5\u53e3\u6709List\u4e0eSet\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Collections\u5219\u662f\u96c6\u5408\u7c7b\u7684\u4e00\u4e2a\u5de5\u5177\u7c7b\/\u5e2e\u52a9\u7c7b<\/strong>\uff0c\u5176\u4e2d\u63d0\u4f9b\u4e86\u4e00\u7cfb\u5217\u9759\u6001\u65b9\u6cd5\uff0c\u7528\u4e8e\u5bf9\u96c6\u5408\u4e2d\u5143\u7d20\u8fdb\u884c\u6392\u5e8f\u3001\u641c\u7d22\u4ee5\u53ca\u7ebf\u7a0b\u5b89\u5168\u7b49\u5404\u79cd\u64cd\u4f5c\u3002<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>1\u3001\u4ec0\u4e48\u662f\u96c6\u5408\uff1f 2\u3001\u5e38\u7528\u7684\u96c6\u5408\u7c7b\u6709\u54ea\u4e9b\uff1f Collection\u96c6\u5408\u4e3b\u8981\u6709List\u548cSet\u4e24\u5927\u63a5\u53e3\uff1a Map\u662f [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":234,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[103,104],"tags":[],"class_list":["post-1389","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/posts\/1389","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/comments?post=1389"}],"version-history":[{"count":2,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/posts\/1389\/revisions"}],"predecessor-version":[{"id":1452,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/posts\/1389\/revisions\/1452"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/media\/234"}],"wp:attachment":[{"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/media?parent=1389"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/categories?post=1389"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zero-zl.cn\/index.php\/wp-json\/wp\/v2\/tags?post=1389"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}