{"id":5240,"date":"2021-07-08T13:13:30","date_gmt":"2021-07-08T05:13:30","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=5240"},"modified":"2021-07-08T13:13:30","modified_gmt":"2021-07-08T05:13:30","slug":"java8-stream-%e5%ae%9e%e7%8e%b0%e5%a4%8d%e6%9d%82%e9%9b%86%e5%90%88%e5%af%b9%e8%b1%a1%e7%9a%84%e5%b7%ae%e9%9b%86%e3%80%81%e5%b9%b6%e9%9b%86%e3%80%81%e4%ba%a4%e9%9b%86","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=5240","title":{"rendered":"Java8 Stream \u5b9e\u73b0\u590d\u6742\u96c6\u5408\u5bf9\u8c61\u7684\u5dee\u96c6\u3001\u5e76\u96c6\u3001\u4ea4\u96c6"},"content":{"rendered":"\n

Java8 Stream \u5b9e\u73b0\u590d\u6742\u96c6\u5408\u5bf9\u8c61\u7684\u5dee\u96c6\u3001\u5e76\u96c6\u3001\u4ea4\u96c6\uff01<\/p>\n\n\n\n

\u6628\u5929\u7fa4\u91cc\u4e00\u4f4d\u7f51\u53cb\u60f3\u8981\u83b7\u53d6\u4e24\u4e2a List \u96c6\u5408\u4e4b\u95f4\u7684\u5dee\u96c6\u3001\u5e76\u96c6\u3001\u4ea4\u96c6\uff01\u7fa4\u91cc\u7f51\u53cb\u7fa4\u7b56\u7fa4\u529b\uff0c\u5f88\u591a\u6709\u4eba\u7ed9\u4ed6\u767e\u5ea6\u641c\u7d22\u5230\u4e86\u4e00\u4e2a\u7ed3\u679c\u3002demo \u6848\u4f8b\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n\n\n\n

import java.util.ArrayList;\nimport java.util.List;\nimport static java.util.stream.Collectors.toList;\n \npublic class Test {\n \n    public static void main(String[] args) {\n        List<String> list1 = new ArrayList<String>();\n        list1.add(\"1\");\n        list1.add(\"2\");\n        list1.add(\"3\");\n        list1.add(\"5\");\n        list1.add(\"6\");\n \n        List<String> list2 = new ArrayList<String>();\n        list2.add(\"2\");\n        list2.add(\"3\");\n        list2.add(\"7\");\n        list2.add(\"8\");\n \n        \/\/ \u4ea4\u96c6\n        List<String> intersection = list1.stream().filter(item -> list2.contains(item)).collect(toList());\n        System.out.println(\"---\u4ea4\u96c6 intersection---\");\n        intersection.parallelStream().forEach(System.out :: println);\n \n        \/\/ \u5dee\u96c6 (list1 - list2)\n        List<String> reduce1 = list1.stream().filter(item -> !list2.contains(item)).collect(toList());\n        System.out.println(\"---\u5dee\u96c6 reduce1 (list1 - list2)---\");\n        reduce1.parallelStream().forEach(System.out :: println);\n \n        \/\/ \u5dee\u96c6 (list2 - list1)\n        List<String> reduce2 = list2.stream().filter(item -> !list1.contains(item)).collect(toList());\n        System.out.println(\"---\u5dee\u96c6 reduce2 (list2 - list1)---\");\n        reduce2.parallelStream().forEach(System.out :: println);\n \n        \/\/ \u5e76\u96c6\n        List<String> listAll = list1.parallelStream().collect(toList());\n        List<String> listAll2 = list2.parallelStream().collect(toList());\n        listAll.addAll(listAll2);\n        System.out.println(\"---\u5e76\u96c6 listAll---\");\n        listAll.parallelStream().forEachOrdered(System.out :: println);\n \n        \/\/ \u53bb\u91cd\u5e76\u96c6\n        List<String> listAllDistinct = listAll.stream().distinct().collect(toList());\n        System.out.println(\"---\u5f97\u5230\u53bb\u91cd\u5e76\u96c6 listAllDistinct---\");\n        listAllDistinct.parallelStream().forEachOrdered(System.out :: println);\n \n        System.out.println(\"---\u539f\u6765\u7684List1---\");\n        list1.parallelStream().forEachOrdered(System.out :: println);\n        System.out.println(\"---\u539f\u6765\u7684List2---\");\n        list2.parallelStream().forEachOrdered(System.out :: println);\n \n    }\n}<\/code><\/pre>\n\n\n\n
\u7136\u540e\u8fd9\u4f4d\u7f51\u53cb\u7167\u7740 demo \u4ee3\u7801\u4fee\u6539\u4e00\u756a\uff0c\u53d1\u73b0\u4e0d\u884c\u3002<\/p>\n\n\n\n
\u867d\u7136\u4e0a\u9762\u7684 demo \u8fd0\u884c\u662f\u53ef\u4ee5\u7684\uff0c\u4f46\u662f\u628a List \u96c6\u5408\u4e2d\u7684 String \u53d8\u6210\u5bf9\u8c61\u540e\uff0c\u5b9e\u73b0\u4e0d\u4e86\u529f\u80fd\u3002<\/p>\n\n\n\n
\u4e8e\u662f\u4ed6\u8d34\u51fa\u4e86\u81ea\u5df1\u7684\u4ee3\u7801\uff0cList<UserDTO><\/code> \u66ff\u6362\u4e86 List<String><\/code>\uff0c\u5176\u4ed6\u4fdd\u6301\u4e0d\u53d8\u3002<\/p>\n\n\n\n
UserDTO \u7684\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n\n\n\n
@Data\npublic class UserDTO{\n    private String id;\n    private String name;\n    private Integer age;\n}<\/code><\/pre>\n\n\n\n
\u4e3a\u4ec0\u4e48 String \u53d8\u6210 UserDTO \u540e\u4e0d\u884c\u4e86\u5462\uff1f<\/p>\n\n\n\n
\u539f\u56e0\u662f\uff0cList \u7684 contains \u65b9\u6cd5\u7528\u7684\u6bd4\u8f83\u662f equals\uff0cUserDTO \u6ca1\u6709\u81ea\u5df1\u91cd\u5199 equals \u65b9\u6cd5\uff0c\u56e0\u6b64\u9ed8\u8ba4\u7684 equals \u6bd4\u8f83\u7684\u662f\u7ee7\u627f Object \u7c7b\u63d0\u4f9b\u7684 equals\u3002Object \u4e2d equals \u65b9\u6cd5\u6bd4\u8f83\u7684\u662f\u4e24\u4e2a\u5f15\u7528\u7684\u5185\u5b58\u5730\u5740\u3002\u56e0\u6b64\uff0ccontains \u540e\u53d1\u73b0\u5bf9\u8c61\u90fd\u4e0d\u76f8\u7b49\uff0c\u5168\u662f\u5dee\u96c6\u3002<\/p>\n\n\n\n
\u90a3\u4e48\u73b0\u5728\u7684\u89e3\u51b3\u65b9\u6cd5\u6709\u4e24\u79cd\uff0c\u4e00\u79cd\u662f\u8ba9 UserDTO \u7c7b\u81ea\u5df1\u91cd\u5199 equals \u65b9\u6cd5\u3002<\/p>\n\n\n\n
\u8fd8\u6709\u4e00\u79cd\u662f\u5148\u627e\u51fa\u8981\u6bd4\u8f83\u7684 id\uff0c\u6216\u8005 name\uff0c\u518d\u53d6\u5bf9\u8c61\u3002<\/p>\n\n\n\n
\u7b2c\u4e00\u79cd\u8fc7\u4e8e\u7b80\u5355\uff0c\u6211\u5c31\u4e0d\u8bf4\u4e86\uff0c\u6211\u4e3b\u8981\u8bf4\u4e00\u8bf4\uff0c\u7b2c\u4e8c\u79cd\u505a\u6cd5\u3002<\/p>\n\n\n\n
package com.stream;\n \nimport java.util.ArrayList;\nimport java.util.List;\nimport java.util.stream.Collectors;\n \n\/**\n *\n * @ClassName: TwoListCopare\n * @Description: \u4e24\u4e2aList<\u5bf9\u8c61>\u53d6\u4ea4\u96c6\\\u5e76\u96c6\\\u5dee\u96c6<\/>\n **\/\npublic class TwoListCopare {\n    public static void main(String[] args) {\n        UserDTO userOld1 = new UserDTO(\"1\",\"aaa\",22);\n        UserDTO userOld2 = new UserDTO(\"2\",\"bbb\",32);\n        UserDTO userOld3 = new UserDTO(\"3\",\"ccc\",11);\n        UserDTO userOld4 = new UserDTO(\"4\",\"ddd\",42);\n        UserDTO userOld5 = new UserDTO(\"5\",\"bbb\",22);\n        UserDTO userOld6 = new UserDTO(\"6\",\"eee\",24);\n \n        UserDTO userNew1 = new UserDTO(\"7\",\"dada\",22);     \/\/\u65b0\u589e\u4e00\u4e2a\n        UserDTO userNew2 = new UserDTO(\"2\",\"bbb\",32);     \/\/\u4e0d\u53d8\u4e00\u4e2a\n        UserDTO userNew3 = new UserDTO(\"3\",\"kaka\",33);     \/\/\u66f4\u65b0\u4e00\u4e2a\n        UserDTO userNew4 = new UserDTO(\"8\",\"dbdb\",42);     \/\/\u65b0\u589e\u4e00\u4e2a\n        UserDTO userNew5 = new UserDTO(\"5\",\"bbb\",100);     \/\/\u66f4\u65b0\u4e00\u4e2a\n        \/\/\u5f53\u7136\uff0c\u5c11\u4e861,4,6\n \n        List<UserDTO> mapAdd = new ArrayList<>();\n \n        List<UserDTO> oldList = new ArrayList<>();\n        List<UserDTO> newList = new ArrayList<>();\n \n        \/\/\u6dfb\u52a0\u8001\u6570\u636e\n        oldList.add(userOld1);\n        oldList.add(userOld2);\n        oldList.add(userOld3);\n        oldList.add(userOld4);\n        oldList.add(userOld5);\n        oldList.add(userOld6);\n        \/\/\u6dfb\u52a0\u65b0\u6570\u636e\n        newList.add(userNew1);\n        newList.add(userNew2);\n        newList.add(userNew3);\n        newList.add(userNew4);\n        newList.add(userNew5);\n \n        \/\/\u53bb\u4ea4\u96c6,\u65e2\u83b7\u53d6id\u76f8\u540c\u7684\u4ea4\u96c6\uff0c\u9700\u8981\u66f4\u65b0\n        \/\/1.\u5148\u63d0\u53d6\u51faid\u548c\u7ed3\u679c\uff0c\u7528map\u5f62\u5f0f\n        List<String> oldIds = new ArrayList<>();\n        List<String> newIds = new ArrayList<>();\n        oldList.stream().forEach(it->oldIds.add(it.getId()));\n        newList.stream().forEach(it->newIds.add(it.getId()));\n\/\/        oldIds.stream().forEach(System.out::println);\n\/\/        newIds.stream().forEach(System.out::println);\n \n        \/\/\u53d6\u4ea4\u96c6id\n        System.out.println(\"-----------------\u4ea4\u96c6----------------------\");\n        List<String> collectUpdate = newIds.stream().filter(it -> oldIds.contains(it)).collect(Collectors.toList());\n        collectUpdate.stream().forEach(System.out::println);\n        \/\/\u53d6\u5bf9\u5e94\u4ea4\u96c6\u7684\u5bf9\u8c61\n        System.out.println(\"------------------\u4ea4\u96c6\u7684\u5bf9\u8c61---------------------\");\n        List<UserDTO> userUpdate = newList.stream().filter(it -> collectUpdate.contains(it.getId())).collect(Collectors.toList());\n        userUpdate.stream().forEach(System.out::println);\n \n        \/\/\u53d6old\u7684\u5dee\u96c6\n        System.out.println(\"-----------------old\u7684\u5dee\u96c6----------------------\");\n        List<String> collectDelete = oldIds.stream().filter(it -> !newIds.contains(it)).collect(Collectors.toList());\n        collectDelete.stream().forEach((System.out::println));\n        \/\/\u53d6\u5bf9\u5e94old\u5dee\u96c6\u5bf9\u8c61\n        System.out.println(\"-----------------old\u5dee\u96c6\u5bf9\u8c61----------------------\");\n        List<UserDTO> userDelete = oldList.stream().filter(it -> collectDelete.contains(it.getId())).collect(Collectors.toList());\n        userDelete.stream().forEach(System.out::println);\n \n        \/\/\u53d6new\u7684\u5dee\u96c6\n        System.out.println(\"-----------------new\u7684\u5dee\u96c6----------------------\");\n        List<String> collectAdd = newIds.stream().filter(it -> !oldIds.contains(it)).collect(Collectors.toList());\n        collectAdd.stream().forEach((System.out::println));\n        \/\/\u53d6\u5bf9\u5e94old\u5dee\u96c6\u5bf9\u8c61\n        System.out.println(\"-------------------old\u5dee\u96c6\u5bf9\u8c61--------------------\");\n        List<UserDTO> userAdd = newList.stream().filter(it -> collectAdd.contains(it.getId())).collect(Collectors.toList());\n        userAdd.stream().forEach(System.out::println);\n \n \n        \/\/\u53d6\u5e76\u96c6\n        System.out.println(\"-------------------\u5e76\u96c6--------------------\");\n        List<String> allIds = new ArrayList<>();\n        \/\/\u83b7\u53d6\u4e00\u4e2a\u5305\u542b\u4e86oldIds\u548cnewIds\u7684\u603b\u7ed3\u5408,\u4f46\u662f\u6ca1\u6709\u53bb\u91cd\n        allIds.addAll(oldIds);\n        allIds.addAll(newIds);\n        \/\/\u53bb\u91cd\uff0c\u83b7\u53d6\u5e76\u96c6ids\u7684\u65b0\u96c6\u5408\n        List<String> joinIds = allIds.stream().distinct().collect(Collectors.toList());\n        joinIds.stream().forEach(System.out::println);\n    }\n}<\/code><\/pre>\n\n\n\n
\"Java8
Java8 Stream \u83b7\u53d6\u4e24\u4e2a List \u590d\u6742\u5bf9\u8c61\u7684\u4ea4\u96c6,\u5e76\u96c6,\u5dee\u96c6<\/figcaption><\/figure>\n\n\n\n
\u6211\u8fd9\u4e2a demo \u4e2d\uff0c\u6211\u53d6\u7684\u662f id\uff0c\u5927\u5bb6\u53ef\u4ee5\u6839\u636e\u9700\u8981\u53d6\u4e0d\u540c\u7684\u5b57\u6bb5\u3002\u6216\u8005\u7ec4\u5408\u5b57\u6bb5\uff0c\u6bd4\u5982\uff0cid + name \u7684\u5f62\u5f0f\u3002<\/p>\n\n\n\n
\u91cd\u5199 equals \u5927\u5bb6\u4e00\u5b9a\u8981\u6ce8\u610f\uff0chashCode \u4e5f\u9700\u8981\u91cd\u5199\u3002<\/p>\n\n\n\n
@Data\npublic class UserDTO{\n    private String id;\n    private String name;\n    private Integer age;\n\n    @Override\n    public boolean equals(Object obj) {\n        if(this == obj){\n            return true;\/\/\u5730\u5740\u76f8\u7b49\n        }\n\n        if(obj == null){\n            return false;\/\/\u975e\u7a7a\u6027\uff1a\u5bf9\u4e8e\u4efb\u610f\u975e\u7a7a\u5f15\u7528x\uff0cx.equals(null)\u5e94\u8be5\u8fd4\u56defalse\u3002\n        }\n\n        if(obj instanceof UserDTO){\n            UserDTO other = (UserDTO) obj;\n            \/\/\u9700\u8981\u6bd4\u8f83\u7684\u5b57\u6bb5\u76f8\u7b49\uff0c\u5219\u8fd9\u4e24\u4e2a\u5bf9\u8c61\u76f8\u7b49\n            if(equalsStr(this.name, other.name)\n                    && equalsStr(this.age, other.age)){\n                return true;\n            }\n        }\n\n        return false;\n    }\n\n    private boolean equalsStr(String str1, String str2){\n        if(StringUtils.isEmpty(str1) && StringUtils.isEmpty(str2)){\n            return true;\n        }\n        if(!StringUtils.isEmpty(str1) && str1.equals(str2)){\n            return true;\n        }\n        return false;\n    }\n\n    @Override\n    public int hashCode() {\n        int result = 17;\n        result = 31 * result + (name == null ? 0 : name.hashCode());\n        result = 31 * result + (age == null ? 0 : age.hashCode());\n        return result;\n    }\n}<\/code><\/pre>\n\n\n\n
\u4ee5\u4e0a\u5185\u5bb9\u6765\u81ea\u7fa4\u53cb\u7684\u667a\u6167\uff0c\u8fd9\u91cc\u5206\u4eab\u51fa\u6765\uff0c\u65b9\u4fbf\u521d\u5b66\u8005\u603b\u7ed3\u77e5\u8bc6\uff01<\/p>\n
\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/<\/p>
\u6700\u540e\uff0c\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u4e2a\u4eba\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u4e1a\u4f59\u8349\uff08yyucao\uff09\uff01\u53ef\u52a0\u4f5c\u8005\u5fae\u4fe1\u53f7\uff1axttblog2<\/font>\u3002\u5907\u6ce8\uff1a\u201c1\u201d\uff0c\u6dfb\u52a0\u535a\u4e3b\u5fae\u4fe1\u62c9\u4f60\u8fdb\u5fae\u4fe1\u7fa4\u3002\u5907\u6ce8\u9519\u8bef\u4e0d\u4f1a\u540c\u610f\u597d\u53cb\u7533\u8bf7\u3002<\/b>\u518d\u6b21\u611f\u8c22\u60a8\u7684\u5173\u6ce8\uff01\u540e\u7eed\u6709\u7cbe\u5f69\u5185\u5bb9\u4f1a\u7b2c\u4e00\u65f6\u95f4\u53d1\u7ed9\u60a8\uff01\u539f\u521b\u6587\u7ae0\u6295\u7a3f\u8bf7\u53d1\u9001\u81f3532009913@qq.com\u90ae\u7bb1\u3002\u5546\u52a1\u5408\u4f5c\u4e5f\u53ef\u6dfb\u52a0\u4f5c\u8005\u5fae\u4fe1\u8fdb\u884c\u8054\u7cfb\uff01<\/p>
\u672c\u6587\u539f\u6587\u51fa\u5904\uff1a\u4e1a\u4f59\u8349<\/a>\uff1a » Java8 Stream \u5b9e\u73b0\u590d\u6742\u96c6\u5408\u5bf9\u8c61\u7684\u5dee\u96c6\u3001\u5e76\u96c6\u3001\u4ea4\u96c6<\/a><\/p>","protected":false},"excerpt":{"rendered":"
Java8 Stream \u5b9e\u73b0\u590d\u6742\u96c6\u5408\u5bf9\u8c61\u7684\u5dee\u96c6\u3001\u5e76\u96c6\u3001\u4ea4\u96c6\uff01 \u6628\u5929\u7fa4\u91cc\u4e00\u4f4d\u7f51\u53cb\u60f3\u8981\u83b7\u53d6\u4e24\u4e2a List \u96c6\u5408\u4e4b […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[1727,618,266,70,547],"class_list":["post-5240","post","type-post","status-publish","format-standard","hentry","category-java","tag-java8","tag-java"],"_links":{"self":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5240","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5240"}],"version-history":[{"count":1,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5240\/revisions"}],"predecessor-version":[{"id":5241,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5240\/revisions\/5241"}],"wp:attachment":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5240"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5240"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5240"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}