\u6700\u8fd1\u53c8\u662f\u4e00\u8f6e\u4ee3\u7801review , \u53d1\u73b0\u4e86\u4e00\u4e9b\u5b9e\u73b0\u53bb\u91cd\u7684\u4ee3\u7801\uff0c\u5728\u4f7f\u7528 list.contain ……<\/p>\n
<\/p>\n
\u6211\u6c89\u601d\uff0c\u662f\u4e0d\u662f\u5176\u5b9e\u5f88\u591a\u521d\u5b66\u8005\u4e5f\u5b58\u5728\u8fd9\u79cd\u53bb\u91cd\u4f7f\u7528\u95ee\u9898\uff1f<\/p>\n
\u6240\u4ee5\u6211\u9009\u62e9\u628a\u8fd9\u4e2a\u4e8b\u60c5\u6574\u51fa\u6765\uff0c\u5206\u4eab\u4e00\u4e0b\u3002<\/p>\n
\u63a8\u8350\u4e00\u4e2a\u5f00\u6e90\u514d\u8d39\u7684 Spring Boot \u5b9e\u6218\u9879\u76ee\uff1a<\/p>\n
https:\/\/github.com\/javastacks\/spring-boot-best-practice<\/a><\/p><\/blockquote>\n
\u2460<\/h2>\n
\u9996\u5148\u662f\u9020\u51fa\u4e00\u4e2a List<String> \u6a21\u62df\u6570\u636e\uff0c\u4e00\u51712W\u6761\uff0c\u91cc\u9762\u6709\u4e00\u534a\u6570\u636e1W\u6761\u662f\u91cd\u590d\u7684:<\/p>\n
public static List<String> getTestList() {\n List<String> list = new ArrayList<>();\n for (int i = 1; i <= 10000; i++) {\n list.add(String.valueOf(i));\n }\n for (int i = 10000; i >= 1; i--) {\n list.add(String.valueOf(i));\n }\n return list;\n}<\/code><\/pre>\n\u5148\u770b\u770b\u6211\u4eec\u7528 contain \u53bb\u91cd\u7684\u4ee3\u7801\uff1a<\/p>\n
\/**\n * \u4f7f\u7528 list.contain \u53bb\u91cd\n *\n * @param testList\n *\/\nprivate static void useContain2Distinct(List<String> testList) {\n System.out.println("contains \u5f00\u59cb\u53bb\u91cd\uff0c\u6761\u6570\uff1a" + testList.size());\n List<String> testListDistinctResult = new ArrayList<>();\n for (String str : testList) {\n if (!testListDistinctResult.contains(str)) {\n testListDistinctResult.add(str);\n }\n }\n System.out.println("contains \u53bb\u91cd\u5b8c\u6bd5\uff0c\u6761\u6570\uff1a" + testListDistinctResult.size());\n}<\/code><\/pre>\n\u6211\u4eec\u8c03\u7528\u4e00\u4e0b\u770b\u770b\u8017\u65f6\uff1a<\/p>\n
public static void main(String[] args) {\n List<String> testList = getTestList();\n StopWatch stopWatch = new StopWatch();\n stopWatch.start();\n useContainDistinct(testList);\n stopWatch.stop();\n System.out.println("\u53bb\u91cd \u6700\u7ec8\u8017\u65f6" + stopWatch.getTotalTimeMillis());\n}<\/code><\/pre>\n\u8017\u65f6\uff1a<\/p>\n
<\/p>\n
\u8bc4\u4ef7\uff1a<\/strong>list.contain \u7684\u6548\u7387\uff0c\u6211\u7684\u5efa\u8bae\u662f\uff0c\u77e5\u9053\u5c31\u884c\uff0c\u522b\u7528\u3002<\/p>\n
\u2461<\/h2>\n
\u4f17\u6240\u5468\u77e5 Set \u4e0d\u5b58\u5728\u91cd\u590d\u6570\u636e\uff0c \u6240\u4ee5\u6211\u4eec\u6765\u770b\u770b\u4f7f\u7528 HashSet \u53bb\u91cd\u7684\u6027\u80fd\uff1a<\/p>\n
ps\uff1a\u8fd9\u91cc\u662f\u91c7\u53d6\u4f7f\u7528 set \u7684 add \u65b9\u6cd5\u505a\u53bb\u91cd<\/p>\n
\/**\n * \u4f7f\u7528set\u53bb\u91cd\n *\n * @param testList\n *\/\nprivate static void useSetDistinct(List<String> testList) {\n System.out.println("HashSet.add \u5f00\u59cb\u53bb\u91cd\uff0c\u6761\u6570\uff1a" + testList.size());\n List<String> testListDistinctResult = new ArrayList<>(new HashSet(testList));\n System.out.println("HashSet.add \u53bb\u91cd\u5b8c\u6bd5\uff0c\u6761\u6570\uff1a" + testListDistinctResult.size());\n}<\/code><\/pre>\n\u6211\u4eec\u8c03\u7528\u4e00\u4e0b\u770b\u770b\u8017\u65f6\uff1a<\/p>\n
public static void main(String[] args) {\n List<String> testList = getTestList();\n StopWatch stopWatch = new StopWatch();\n stopWatch.start();\n useSetDistinct(testList);\n stopWatch.stop();\n System.out.println("\u53bb\u91cd \u6700\u7ec8\u8017\u65f6" + stopWatch.getTotalTimeMillis());\n}<\/code><\/pre>\n\u8017\u65f6\uff1a<\/p>\n
<\/p>\n
\u8bc4\u4ef7\uff1a<\/strong>HashSet \u7684\u6548\u7387\uff0c\u6211\u7684\u5efa\u8bae\u662f\u63a8\u8350\u3002<\/p>\n
\u2462<\/h2>\n
\u4e3a\u4ec0\u4e48\u8017\u65f6\u5dee\u8ddd\u8fd9\u4e48\u5927\uff1f<\/p>\n
\u4e0d\u591a\u8bf4\uff0c\u6211\u4eec\u770b\u6e90\u7801\uff1a<\/p>\n
list.contains(o)\uff1a<\/p>\n
<\/p>\n
\u53ef\u4ee5\u770b\u5230\u91cc\u9762\u7528\u5230\u4e86 index(o) \uff1a<\/p>\n
<\/p>\n
\u65f6\u95f4\u590d\u6742\u5ea6 \uff1aO(n) n: \u5143\u7d20\u4e2a\u6570<\/p>\n
\u90a3\u4e48\u6211\u4eec\u770b\u770b set.add(o) \u662f\u600e\u4e48\u6837\u7684 \uff1a<\/p>\n
<\/p>\n
map\u7684add , \u8001\u751f\u5e38\u8c08\u5c31\u4e0d\u8c08\u4e86\uff0chash\u5b8c \u76f4\u63a5\u585e\u5230\u67d0\u4e2a\u4f4d\u7f6e\uff0c \u65f6\u95f4\u590d\u6742\u5ea6 \uff1aO(1) \u3002<\/p>\n
\u6240\u4ee5 O(n) \u548c O(1) \u8c01\u5feb\u8c01\u6162\uff1f\u663e\u7136\u3002<\/p>\n
<\/p>\n
\u65f6\u95f4\u590d\u6742\u5ea6\u4e5f\u662f\uff1aO(1)<\/p>\n
<\/p>\n
\u2463<\/h2>\n
\u90a3\u4e48\u6211\u4eec\u6700\u540e\u518d\u770b\u770b\u522b\u7684\u53bb\u91cd\uff1a<\/p>\n
\u53ccfor\u5faa\u73af \uff0cremove\u53bb\u91cd<\/p>\n
\/**\n * \u4f7f\u7528\u53ccfor\u5faa\u73af\u53bb\u91cd\n * @param testList\n *\/\nprivate static void use2ForDistinct(List<String> testList) {\n System.out.println("list \u53cc\u5faa\u73af \u5f00\u59cb\u53bb\u91cd\uff0c\u6761\u6570\uff1a" + testList.size());\n for (int i = 0; i < testList.size(); i++) {\n for (int j = i + 1; j < testList.size(); j++) {\n if (testList.get(i).equals(testList.get(j))) {\n testList.remove(j);\n }\n }\n }\n System.out.println("list \u53cc\u5faa\u73af \u53bb\u91cd\u5b8c\u6bd5\uff0c\u6761\u6570\uff1a" + testList.size());\n}\npublic static void main(String[] args) {\n List<String> testList = getTestList();\n StopWatch stopWatch = new StopWatch();\n stopWatch.start();\n use2ForDistinct(testList);\n stopWatch.stop();\n System.out.println("\u53bb\u91cd \u6700\u7ec8\u8017\u65f6" + stopWatch.getTotalTimeMillis());\n}<\/code><\/pre>\n\u8017\u65f6\uff1a<\/p>\n
<\/p>\n
\u8bc4\u4ef7\uff1a<\/strong>\u77e5\u9053\u5c31\u884c\uff0c\u56fe\u4e2a\u4e50\uff0c\u522b\u7528\uff0c\u8d3c\u6162\uff0c\u800c\u4e14\u4ee3\u7801\u770b\u8d77\u6765\u4e71<\/p>\n
stream\u7684distinct\u53bb\u91cd\uff1a<\/p>\n
\/**\n * \u4f7f\u7528Stream \u53bb\u91cd\n *\n * @param testList\n *\/\nprivate static void useStreamDistinct(List<String> testList) {\n System.out.println("stream \u5f00\u59cb\u53bb\u91cd\uff0c\u6761\u6570\uff1a" + testList.size());\n List<String> testListDistinctResult = testList.stream().distinct().collect(Collectors.toList());\n System.out.println("stream \u53bb\u91cd\u5b8c\u6bd5\uff0c\u6761\u6570\uff1a" + testListDistinctResult.size());\n}\npublic static void main(String[] args) {\n List<String> testList = getTestList();\n StopWatch stopWatch = new StopWatch();\n stopWatch.start();\n useStreamDistinct(testList);\n stopWatch.stop();\n System.out.println("\u53bb\u91cd \u6700\u7ec8\u8017\u65f6" + stopWatch.getTotalTimeMillis());\n}<\/code><\/pre>\n\u8017\u65f6\uff1a<\/p>\n
<\/p>\n
\u8bc4\u4ef7\uff1a<\/strong>\u8fd8\u4e0d\u9519\uff0c\u4e3b\u8981\u662f\u4ee3\u7801\u4e5f\u86ee\u7b80\u6d01\uff0c\u6709\u4e00\u70b9\u70b9\u52a8\u5fc3\u3002<\/p>\n
\u6765\u6e90\uff1ablog.csdn.net\/qq_35387940\/article\/details\/129885310<\/p>\n
\u8fd1\u671f\u70ed\u6587\u63a8\u8350\uff1a<\/strong><\/p>\n
1.1,000+ \u9053 Java\u9762\u8bd5\u9898\u53ca\u7b54\u6848\u6574\u7406(2022\u6700\u65b0\u7248)<\/a><\/p>\n
2.\u52b2\u7206\uff01Java \u534f\u7a0b\u8981\u6765\u4e86\u3002\u3002\u3002<\/a><\/p>\n
3.Spring Boot 2.x \u6559\u7a0b\uff0c\u592a\u5168\u4e86\uff01<\/a><\/p>\n
4.\u522b\u518d\u5199\u6ee1\u5c4f\u7684\u7206\u7206\u7206\u70b8\u7c7b\u4e86\uff0c\u8bd5\u8bd5\u88c5\u9970\u5668\u6a21\u5f0f\uff0c\u8fd9\u624d\u662f\u4f18\u96c5\u7684\u65b9\u5f0f\uff01\uff01<\/a><\/p>\n