{"id":5298,"date":"2021-12-08T18:05:13","date_gmt":"2021-12-08T10:05:13","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=5298"},"modified":"2021-12-08T18:05:13","modified_gmt":"2021-12-08T10:05:13","slug":"java8-stream%ef%bc%9a2%e4%b8%87%e5%ad%9720%e4%b8%aa%e5%ae%9e%e4%be%8b%ef%bc%8c%e7%8e%a9%e8%bd%ac%e9%9b%86%e5%90%88%e7%9a%84%e7%ad%9b%e9%80%89%e3%80%81%e5%bd%92%e7%ba%a6%e3%80%81%e5%88%86%e7%bb%84","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=5298","title":{"rendered":"Java8 Stream\uff1a2\u4e07\u5b5720\u4e2a\u5b9e\u4f8b\uff0c\u73a9\u8f6c\u96c6\u5408\u7684\u7b5b\u9009\u3001\u5f52\u7ea6\u3001\u5206\u7ec4\u3001\u805a\u5408"},"content":{"rendered":"\n
\"Java8
Java8 Stream<\/figcaption><\/figure>\n\n\n\n

\u5148\u8d34\u4e0a\u51e0\u4e2a\u6848\u4f8b\uff0c\u6c34\u5e73\u9ad8\u8d85\u7684\u540c\u5b66\u53ef\u4ee5\u6311\u6218\u4e00\u4e0b\uff1a<\/p>\n\n\n\n

  1. \u4ece\u5458\u5de5\u96c6\u5408\u4e2d\u7b5b\u9009\u51fasalary\u5927\u4e8e8000\u7684\u5458\u5de5\uff0c\u5e76\u653e\u7f6e\u5230\u65b0\u7684\u96c6\u5408\u91cc\u3002<\/li>
  2. \u7edf\u8ba1\u5458\u5de5\u7684\u6700\u9ad8\u85aa\u8d44\u3001\u5e73\u5747\u85aa\u8d44\u3001\u85aa\u8d44\u4e4b\u548c\u3002<\/li>
  3. \u5c06\u5458\u5de5\u6309\u85aa\u8d44\u4ece\u9ad8\u5230\u4f4e\u6392\u5e8f\uff0c\u540c\u6837\u85aa\u8d44\u8005\u5e74\u9f84\u5c0f\u8005\u5728\u524d\u3002<\/li>
  4. \u5c06\u5458\u5de5\u6309\u6027\u522b\u5206\u7c7b\uff0c\u5c06\u5458\u5de5\u6309\u6027\u522b\u548c\u5730\u533a\u5206\u7c7b\uff0c\u5c06\u5458\u5de5\u6309\u85aa\u8d44\u662f\u5426\u9ad8\u4e8e8000\u5206\u4e3a\u4e24\u90e8\u5206\u3002<\/li><\/ol>\n\n\n\n

    \u7528\u4f20\u7edf\u7684\u8fed\u4ee3\u5904\u7406\u4e5f\u4e0d\u662f\u5f88\u96be\uff0c\u4f46\u4ee3\u7801\u5c31\u663e\u5f97\u5197\u4f59\u4e86\uff0c\u8ddfStream\u76f8\u6bd4\u9ad8\u4e0b\u7acb\u5224\u3002<\/p>\n\n\n\n

    1 Stream\u6982\u8ff0<\/h2>\n\n\n\n

    Java 8 \u662f\u4e00\u4e2a\u975e\u5e38\u6210\u529f\u7684\u7248\u672c\uff0c\u8fd9\u4e2a\u7248\u672c\u65b0\u589e\u7684Stream<\/code>\uff0c\u914d\u5408\u540c\u7248\u672c\u51fa\u73b0\u7684 Lambda<\/code> \uff0c\u7ed9\u6211\u4eec\u64cd\u4f5c\u96c6\u5408\uff08Collection\uff09\u63d0\u4f9b\u4e86\u6781\u5927\u7684\u4fbf\u5229\u3002<\/p>\n\n\n\n

    \u90a3\u4e48\u4ec0\u4e48\u662fStream<\/code>\uff1f<\/p>\n\n\n\n

    \u275d<\/strong><\/p>

    Stream<\/code>\u5c06\u8981\u5904\u7406\u7684\u5143\u7d20\u96c6\u5408\u770b\u4f5c\u4e00\u79cd\u6d41\uff0c\u5728\u6d41\u7684\u8fc7\u7a0b\u4e2d\uff0c\u501f\u52a9Stream API<\/code>\u5bf9\u6d41\u4e2d\u7684\u5143\u7d20\u8fdb\u884c\u64cd\u4f5c\uff0c\u6bd4\u5982\uff1a\u7b5b\u9009\u3001\u6392\u5e8f\u3001\u805a\u5408\u7b49\u3002\u275e<\/p><\/blockquote>\n\n\n\n

    Stream<\/code>\u53ef\u4ee5\u7531\u6570\u7ec4\u6216\u96c6\u5408\u521b\u5efa\uff0c\u5bf9\u6d41\u7684\u64cd\u4f5c\u5206\u4e3a\u4e24\u79cd\uff1a<\/p>\n\n\n\n

    1. \u4e2d\u95f4\u64cd\u4f5c\uff0c\u6bcf\u6b21\u8fd4\u56de\u4e00\u4e2a\u65b0\u7684\u6d41\uff0c\u53ef\u4ee5\u6709\u591a\u4e2a\u3002<\/li>
    2. \u7ec8\u7aef\u64cd\u4f5c\uff0c\u6bcf\u4e2a\u6d41\u53ea\u80fd\u8fdb\u884c\u4e00\u6b21\u7ec8\u7aef\u64cd\u4f5c\uff0c\u7ec8\u7aef\u64cd\u4f5c\u7ed3\u675f\u540e\u6d41\u65e0\u6cd5\u518d\u6b21\u4f7f\u7528\u3002\u7ec8\u7aef\u64cd\u4f5c\u4f1a\u4ea7\u751f\u4e00\u4e2a\u65b0\u7684\u96c6\u5408\u6216\u503c\u3002<\/li><\/ol>\n\n\n\n

      \u53e6\u5916\uff0cStream<\/code>\u6709\u51e0\u4e2a\u7279\u6027\uff1a<\/p>\n\n\n\n

      1. stream\u4e0d\u5b58\u50a8\u6570\u636e\uff0c\u800c\u662f\u6309\u7167\u7279\u5b9a\u7684\u89c4\u5219\u5bf9\u6570\u636e\u8fdb\u884c\u8ba1\u7b97\uff0c\u4e00\u822c\u4f1a\u8f93\u51fa\u7ed3\u679c\u3002<\/li>
      2. stream\u4e0d\u4f1a\u6539\u53d8\u6570\u636e\u6e90\uff0c\u901a\u5e38\u60c5\u51b5\u4e0b\u4f1a\u4ea7\u751f\u4e00\u4e2a\u65b0\u7684\u96c6\u5408\u6216\u4e00\u4e2a\u503c\u3002<\/li>
      3. stream\u5177\u6709\u5ef6\u8fdf\u6267\u884c\u7279\u6027\uff0c\u53ea\u6709\u8c03\u7528\u7ec8\u7aef\u64cd\u4f5c\u65f6\uff0c\u4e2d\u95f4\u64cd\u4f5c\u624d\u4f1a\u6267\u884c\u3002<\/li><\/ol>\n\n\n\n

        2 Stream\u7684\u521b\u5efa<\/h2>\n\n\n\n

        Stream<\/code>\u53ef\u4ee5\u901a\u8fc7\u96c6\u5408\u6570\u7ec4\u521b\u5efa\u3002<\/p>\n\n\n\n

        1\u3001\u901a\u8fc7 java.util.Collection.stream()<\/code> \u65b9\u6cd5\u7528\u96c6\u5408\u521b\u5efa\u6d41<\/p>\n\n\n\n

        List<String>\u00a0list\u00a0=\u00a0Arrays.asList(\"a\",\u00a0\"b\",\u00a0\"c\");\/\/\u00a0\u521b\u5efa\u4e00\u4e2a\u987a\u5e8f\u6d41Stream<String>\u00a0stream\u00a0=\u00a0list.stream();\/\/\u00a0\u521b\u5efa\u4e00\u4e2a\u5e76\u884c\u6d41Stream<String>\u00a0parallelStream\u00a0=\u00a0list.parallelStream();<\/code><\/pre>\n\n\n\n
        2\u3001\u4f7f\u7528java.util.Arrays.stream(T[] array)<\/code>\u65b9\u6cd5\u7528\u6570\u7ec4\u521b\u5efa\u6d41<\/p>\n\n\n\n
        int[]\u00a0array={1,3,5,6,8};IntStream\u00a0stream\u00a0=\u00a0Arrays.stream(array);<\/code><\/pre>\n\n\n\n
        3\u3001\u4f7f\u7528Stream<\/code>\u7684\u9759\u6001\u65b9\u6cd5\uff1aof()\u3001iterate()\u3001generate()<\/code><\/p>\n\n\n\n
        Stream<Integer>\u00a0stream\u00a0=\u00a0Stream.of(1,\u00a02,\u00a03,\u00a04,\u00a05,\u00a06);Stream<Integer>\u00a0stream2\u00a0=\u00a0Stream.iterate(0,\u00a0(x)\u00a0->\u00a0x\u00a0+\u00a03).limit(4);stream2.forEach(System.out::println);Stream<Double>\u00a0stream3\u00a0=\u00a0Stream.generate(Math::random).limit(3);stream3.forEach(System.out::println);<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        0 3 6 9
        \n0.6796156909271994
        \n0.1914314208854283
        \n0.8116932592396652\u275e<\/p><\/blockquote>\n\n\n\n
        \u300cstream<\/code>\u548cparallelStream<\/code>\u7684\u7b80\u5355\u533a\u5206\uff1a\u300d<\/strong> stream<\/code>\u662f\u987a\u5e8f\u6d41\uff0c\u7531\u4e3b\u7ebf\u7a0b\u6309\u987a\u5e8f\u5bf9\u6d41\u6267\u884c\u64cd\u4f5c\uff0c\u800cparallelStream<\/code>\u662f\u5e76\u884c\u6d41\uff0c\u5185\u90e8\u4ee5\u591a\u7ebf\u7a0b\u5e76\u884c\u6267\u884c\u7684\u65b9\u5f0f\u5bf9\u6d41\u8fdb\u884c\u64cd\u4f5c\uff0c\u4f46\u524d\u63d0\u662f\u6d41\u4e2d\u7684\u6570\u636e\u5904\u7406\u6ca1\u6709\u987a\u5e8f\u8981\u6c42\u3002\u4f8b\u5982\u7b5b\u9009\u96c6\u5408\u4e2d\u7684\u5947\u6570\uff0c\u4e24\u8005\u7684\u5904\u7406\u4e0d\u540c\u4e4b\u5904\uff1a<\/p>\n\n\n\n
        \"\u5e76\u884c\u6d41Stream\u4e0e\u987a\u5e8f\u6d41Stream\"
        \u5e76\u884c\u6d41Stream\u4e0e\u987a\u5e8f\u6d41Stream<\/figcaption><\/figure>\n\n\n\n
        \u5982\u679c\u6d41\u4e2d\u7684\u6570\u636e\u91cf\u8db3\u591f\u5927\uff0c\u5e76\u884c\u6d41\u53ef\u4ee5\u52a0\u5feb\u5904\u901f\u5ea6\u3002<\/p>\n\n\n\n
        \u9664\u4e86\u76f4\u63a5\u521b\u5efa\u5e76\u884c\u6d41\uff0c\u8fd8\u53ef\u4ee5\u901a\u8fc7parallel()<\/code>\u628a\u987a\u5e8f\u6d41\u8f6c\u6362\u6210\u5e76\u884c\u6d41\uff1a<\/p>\n\n\n\n
        Optional<Integer>\u00a0findFirst\u00a0=\u00a0list.stream().parallel().filter(x->x>6).findFirst();<\/code><\/pre>\n\n\n\n
        3 Stream\u7684\u4f7f\u7528<\/h2>\n\n\n\n
        \u5728\u4f7f\u7528stream\u4e4b\u524d\uff0c\u5148\u7406\u89e3\u4e00\u4e2a\u6982\u5ff5\uff1aOptional<\/code> \u3002<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        Optional<\/code>\u7c7b\u662f\u4e00\u4e2a\u53ef\u4ee5\u4e3anull<\/code>\u7684\u5bb9\u5668\u5bf9\u8c61\u3002\u5982\u679c\u503c\u5b58\u5728\u5219isPresent()<\/code>\u65b9\u6cd5\u4f1a\u8fd4\u56detrue<\/code>\uff0c\u8c03\u7528get()<\/code>\u65b9\u6cd5\u4f1a\u8fd4\u56de\u8be5\u5bf9\u8c61\u3002\u275e<\/p><\/blockquote>\n\n\n\n
        \u300c\u63a5\u4e0b\u6765\uff0c\u5927\u6279\u4ee3\u7801\u5411\u4f60\u88ad\u6765\uff01\u6211\u5c06\u752820\u4e2a\u6848\u4f8b\u5c06Stream\u7684\u4f7f\u7528\u6574\u5f97\u660e\u660e\u767d\u767d\uff0c\u53ea\u8981\u8ddf\u7740\u6572\u4e00\u904d\u4ee3\u7801\uff0c\u5c31\u80fd\u5f88\u597d\u5730\u638c\u63e1\u3002\u300d<\/strong><\/p>\n\n\n\n
        \"\u4ee3\u7801\u6709\u6bd2\"
        \u4ee3\u7801\u6709\u6bd2<\/figcaption><\/figure>\n\n\n\n
        \u6848\u4f8b\u4f7f\u7528\u7684\u5458\u5de5\u7c7b<\/h2>\n\n\n\n
        \u8fd9\u662f\u540e\u9762\u6848\u4f8b\u4e2d\u4f7f\u7528\u7684\u5458\u5de5\u7c7b\uff1a<\/p>\n\n\n\n
        List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a0\"male\",\u00a0\"New\u00a0York\"));personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a0\"male\",\u00a0\"Washington\"));personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a0\"female\",\u00a0\"Washington\"));personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a0\"female\",\u00a0\"New\u00a0York\"));personList.add(new\u00a0Person(\"Owen\",\u00a09500,\u00a0\"male\",\u00a0\"New\u00a0York\"));personList.add(new\u00a0Person(\"Alisa\",\u00a07900,\u00a0\"female\",\u00a0\"New\u00a0York\"));class\u00a0Person\u00a0{\u00a0private\u00a0String\u00a0name;\u00a0\u00a0\/\/\u00a0\u59d3\u540d\u00a0private\u00a0int\u00a0salary;\u00a0\/\/\u00a0\u85aa\u8d44\u00a0private\u00a0int\u00a0age;\u00a0\/\/\u00a0\u5e74\u9f84\u00a0private\u00a0String\u00a0sex;\u00a0\/\/\u6027\u522b\u00a0private\u00a0String\u00a0area;\u00a0\u00a0\/\/\u00a0\u5730\u533a\u00a0\/\/\u00a0\u6784\u9020\u65b9\u6cd5\u00a0public\u00a0Person(String\u00a0name,\u00a0int\u00a0salary,\u00a0int\u00a0age,String\u00a0sex,String\u00a0area)\u00a0{\u00a0\u00a0this.name\u00a0=\u00a0name;\u00a0\u00a0this.salary\u00a0=\u00a0salary;\u00a0\u00a0this.age\u00a0=\u00a0age;\u00a0\u00a0this.sex\u00a0=\u00a0sex;\u00a0\u00a0this.area\u00a0=\u00a0area;\u00a0}\u00a0\/\/\u00a0\u7701\u7565\u4e86get\u548cset\uff0c\u8bf7\u81ea\u884c\u6dfb\u52a0}<\/code><\/pre>\n\n\n\n
        3.1 \u904d\u5386\/\u5339\u914d\uff08foreach\/find\/match\uff09<\/h2>\n\n\n\n
        Stream<\/code>\u4e5f\u662f\u652f\u6301\u7c7b\u4f3c\u96c6\u5408\u7684\u904d\u5386\u548c\u5339\u914d\u5143\u7d20\u7684\uff0c\u53ea\u662fStream<\/code>\u4e2d\u7684\u5143\u7d20\u662f\u4ee5Optional<\/code>\u7c7b\u578b\u5b58\u5728\u7684\u3002Stream<\/code>\u7684\u904d\u5386\u3001\u5339\u914d\u975e\u5e38\u7b80\u5355\u3002<\/p>\n\n\n\n
        \"Stream\u904d\u5386\/\u5339\u914d\"
        Stream\u904d\u5386\/\u5339\u914d<\/figcaption><\/figure>\n\n\n\n
        \/\/\u00a0import\u5df2\u7701\u7565\uff0c\u8bf7\u81ea\u884c\u6dfb\u52a0\uff0c\u540e\u9762\u4ee3\u7801\u4ea6\u662fpublic\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0List<Integer>\u00a0list\u00a0=\u00a0Arrays.asList(7,\u00a06,\u00a09,\u00a03,\u00a08,\u00a02,\u00a01);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u904d\u5386\u8f93\u51fa\u7b26\u5408\u6761\u4ef6\u7684\u5143\u7d20\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0list.stream().filter(x\u00a0->\u00a0x\u00a0>\u00a06).forEach(System.out::println);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u5339\u914d\u7b2c\u4e00\u4e2a\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Optional<Integer>\u00a0findFirst\u00a0=\u00a0list.stream().filter(x\u00a0->\u00a0x\u00a0>\u00a06).findFirst();\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u5339\u914d\u4efb\u610f\uff08\u9002\u7528\u4e8e\u5e76\u884c\u6d41\uff09\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Optional<Integer>\u00a0findAny\u00a0=\u00a0list.parallelStream().filter(x\u00a0->\u00a0x\u00a0>\u00a06).findAny();\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u662f\u5426\u5305\u542b\u7b26\u5408\u7279\u5b9a\u6761\u4ef6\u7684\u5143\u7d20\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0boolean\u00a0anyMatch\u00a0=\u00a0list.stream().anyMatch(x\u00a0->\u00a0x\u00a0>\u00a06);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0System.out.println(\"\u5339\u914d\u7b2c\u4e00\u4e2a\u503c\uff1a\"\u00a0+\u00a0findFirst.get());\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0System.out.println(\"\u5339\u914d\u4efb\u610f\u4e00\u4e2a\u503c\uff1a\"\u00a0+\u00a0findAny.get());\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0System.out.println(\"\u662f\u5426\u5b58\u5728\u5927\u4e8e6\u7684\u503c\uff1a\"\u00a0+\u00a0anyMatch);\u00a0\u00a0\u00a0\u00a0}}<\/code><\/pre>\n\n\n\n
        3.2 \u7b5b\u9009\uff08filter\uff09<\/h2>\n\n\n\n
        \u7b5b\u9009\uff0c\u662f\u6309\u7167\u4e00\u5b9a\u7684\u89c4\u5219\u6821\u9a8c\u6d41\u4e2d\u7684\u5143\u7d20\uff0c\u5c06\u7b26\u5408\u6761\u4ef6\u7684\u5143\u7d20\u63d0\u53d6\u5230\u65b0\u7684\u6d41\u4e2d\u7684\u64cd\u4f5c\u3002<\/p>\n\n\n\n
        \"Stream\u7b5b\u9009filter\"
        Stream\u7b5b\u9009filter<\/figcaption><\/figure>\n\n\n\n
        \u300c\u6848\u4f8b\u4e00\uff1a\u7b5b\u9009\u51faInteger<\/code>\u96c6\u5408\u4e2d\u5927\u4e8e7\u7684\u5143\u7d20\uff0c\u5e76\u6253\u5370\u51fa\u6765\u300d<\/strong><\/p>\n\n\n\n
        public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Integer>\u00a0list\u00a0=\u00a0Arrays.asList(6,\u00a07,\u00a03,\u00a08,\u00a01,\u00a02,\u00a09);\u00a0\u00a0Stream<Integer>\u00a0stream\u00a0=\u00a0list.stream();\u00a0\u00a0stream.filter(x\u00a0->\u00a0x\u00a0>\u00a07).forEach(System.out::println);\u00a0}}<\/code><\/pre>\n\n\n\n
        \u9884\u671f\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        8 9\u275e<\/p><\/blockquote>\n\n\n\n
        \u300c\u6848\u4f8b\u4e8c\uff1a \u7b5b\u9009\u5458\u5de5\u4e2d\u5de5\u8d44\u9ad8\u4e8e8000\u7684\u4eba\uff0c\u5e76\u5f62\u6210\u65b0\u7684\u96c6\u5408\u3002\u300d<\/strong> \u5f62\u6210\u65b0\u96c6\u5408\u4f9d\u8d56collect<\/code>\uff08\u6536\u96c6\uff09\uff0c\u540e\u6587\u6709\u8be6\u7ec6\u4ecb\u7ecd\u3002<\/p>\n\n\n\n
        public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a024,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Owen\",\u00a09500,\u00a025,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Alisa\",\u00a07900,\u00a026,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0List<String>\u00a0fiterList\u00a0=\u00a0personList.stream().filter(x\u00a0->\u00a0x.getSalary()\u00a0>\u00a08000).map(Person::getName)\u00a0\u00a0\u00a0\u00a0.collect(Collectors.toList());\u00a0\u00a0System.out.print(\"\u9ad8\u4e8e8000\u7684\u5458\u5de5\u59d3\u540d\uff1a\"\u00a0+\u00a0fiterList);\u00a0}}<\/code><\/pre>\n\n\n\n
        \u8fd0\u884c\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        \u9ad8\u4e8e8000\u7684\u5458\u5de5\u59d3\u540d\uff1a[Tom, Anni, Owen]\u275e<\/p><\/blockquote>\n\n\n\n
        3.3 \u805a\u5408\uff08max\/min\/count)<\/h2>\n\n\n\n
        max<\/code>\u3001min<\/code>\u3001count<\/code>\u8fd9\u4e9b\u5b57\u773c\u4f60\u4e00\u5b9a\u4e0d\u964c\u751f\uff0c\u6ca1\u9519\uff0c\u5728mysql\u4e2d\u6211\u4eec\u5e38\u7528\u5b83\u4eec\u8fdb\u884c\u6570\u636e\u7edf\u8ba1\u3002Java stream\u4e2d\u4e5f\u5f15\u5165\u4e86\u8fd9\u4e9b\u6982\u5ff5\u548c\u7528\u6cd5\uff0c\u6781\u5927\u5730\u65b9\u4fbf\u4e86\u6211\u4eec\u5bf9\u96c6\u5408\u3001\u6570\u7ec4\u7684\u6570\u636e\u7edf\u8ba1\u5de5\u4f5c\u3002<\/p>\n\n\n\n
        \"Stream\u805a\u5408max\/min\/count\"
        Stream\u805a\u5408max\/min\/count<\/figcaption><\/figure>\n\n\n\n
        \u300c\u6848\u4f8b\u4e00\uff1a\u83b7\u53d6String<\/code>\u96c6\u5408\u4e2d\u6700\u957f\u7684\u5143\u7d20\u3002\u300d<\/strong><\/p>\n\n\n\n
        public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<String>\u00a0list\u00a0=\u00a0Arrays.asList(\"adnm\",\u00a0\"admmt\",\u00a0\"pot\",\u00a0\"xbangd\",\u00a0\"weoujgsd\");\u00a0\u00a0Optional<String>\u00a0max\u00a0=\u00a0list.stream().max(Comparator.comparing(String::length));\u00a0\u00a0System.out.println(\"\u6700\u957f\u7684\u5b57\u7b26\u4e32\uff1a\"\u00a0+\u00a0max.get());\u00a0}}<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        \u6700\u957f\u7684\u5b57\u7b26\u4e32\uff1aweoujgsd\u275e<\/p><\/blockquote>\n\n\n\n
        \u300c\u6848\u4f8b\u4e8c\uff1a\u83b7\u53d6Integer<\/code>\u96c6\u5408\u4e2d\u7684\u6700\u5927\u503c\u3002\u300d<\/strong><\/p>\n\n\n\n
        public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Integer>\u00a0list\u00a0=\u00a0Arrays.asList(7,\u00a06,\u00a09,\u00a04,\u00a011,\u00a06);\u00a0\u00a0\/\/\u00a0\u81ea\u7136\u6392\u5e8f\u00a0\u00a0Optional<Integer>\u00a0max\u00a0=\u00a0list.stream().max(Integer::compareTo);\u00a0\u00a0\/\/\u00a0\u81ea\u5b9a\u4e49\u6392\u5e8f\u00a0\u00a0Optional<Integer>\u00a0max2\u00a0=\u00a0list.stream().max(new\u00a0Comparator<Integer>()\u00a0{\u00a0\u00a0\u00a0@Override\u00a0\u00a0\u00a0public\u00a0int\u00a0compare(Integer\u00a0o1,\u00a0Integer\u00a0o2)\u00a0{\u00a0\u00a0\u00a0\u00a0return\u00a0o1.compareTo(o2);\u00a0\u00a0\u00a0}\u00a0\u00a0});\u00a0\u00a0System.out.println(\"\u81ea\u7136\u6392\u5e8f\u7684\u6700\u5927\u503c\uff1a\"\u00a0+\u00a0max.get());\u00a0\u00a0System.out.println(\"\u81ea\u5b9a\u4e49\u6392\u5e8f\u7684\u6700\u5927\u503c\uff1a\"\u00a0+\u00a0max2.get());\u00a0}}<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        \u81ea\u7136\u6392\u5e8f\u7684\u6700\u5927\u503c\uff1a11
        \n\u81ea\u5b9a\u4e49\u6392\u5e8f\u7684\u6700\u5927\u503c\uff1a11\u275e<\/p><\/blockquote>\n\n\n\n
        \u300c\u6848\u4f8b\u4e09\uff1a\u83b7\u53d6\u5458\u5de5\u5de5\u8d44\u6700\u9ad8\u7684\u4eba\u3002\u300d<\/strong><\/p>\n\n\n\n
        public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a024,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Owen\",\u00a09500,\u00a025,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Alisa\",\u00a07900,\u00a026,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0Optional<Person>\u00a0max\u00a0=\u00a0personList.stream().max(Comparator.comparingInt(Person::getSalary));\u00a0\u00a0System.out.println(\"\u5458\u5de5\u5de5\u8d44\u6700\u5927\u503c\uff1a\"\u00a0+\u00a0max.get().getSalary());\u00a0}}<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        \u5458\u5de5\u5de5\u8d44\u6700\u5927\u503c\uff1a9500\u275e<\/p><\/blockquote>\n\n\n\n
        \u300c\u6848\u4f8b\u56db\uff1a\u8ba1\u7b97Integer<\/code>\u96c6\u5408\u4e2d\u5927\u4e8e6\u7684\u5143\u7d20\u7684\u4e2a\u6570\u3002\u300d<\/strong><\/p>\n\n\n\n
        import\u00a0java.util.Arrays;import\u00a0java.util.List;public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Integer>\u00a0list\u00a0=\u00a0Arrays.asList(7,\u00a06,\u00a04,\u00a08,\u00a02,\u00a011,\u00a09);\u00a0\u00a0long\u00a0count\u00a0=\u00a0list.stream().filter(x\u00a0->\u00a0x\u00a0>\u00a06).count();\u00a0\u00a0System.out.println(\"list\u4e2d\u5927\u4e8e6\u7684\u5143\u7d20\u4e2a\u6570\uff1a\"\u00a0+\u00a0count);\u00a0}}<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
        \u275d<\/strong><\/p>
        list\u4e2d\u5927\u4e8e6\u7684\u5143\u7d20\u4e2a\u6570\uff1a4\u275e<\/p><\/blockquote>\n\n\n\n
        3.4 \u6620\u5c04(map\/flatMap)<\/h2>\n\n\n\n
        \u6620\u5c04\uff0c\u53ef\u4ee5\u5c06\u4e00\u4e2a\u6d41\u7684\u5143\u7d20\u6309\u7167\u4e00\u5b9a\u7684\u6620\u5c04\u89c4\u5219\u6620\u5c04\u5230\u53e6\u4e00\u4e2a\u6d41\u4e2d\u3002\u5206\u4e3amap<\/code>\u548cflatMap<\/code>\uff1a<\/p>\n\n\n\n
        • map<\/code>\uff1a\u63a5\u6536\u4e00\u4e2a\u51fd\u6570\u4f5c\u4e3a\u53c2\u6570\uff0c\u8be5\u51fd\u6570\u4f1a\u88ab\u5e94\u7528\u5230\u6bcf\u4e2a\u5143\u7d20\u4e0a\uff0c\u5e76\u5c06\u5176\u6620\u5c04\u6210\u4e00\u4e2a\u65b0\u7684\u5143\u7d20\u3002<\/li>
        • flatMap<\/code>\uff1a\u63a5\u6536\u4e00\u4e2a\u51fd\u6570\u4f5c\u4e3a\u53c2\u6570\uff0c\u5c06\u6d41\u4e2d\u7684\u6bcf\u4e2a\u503c\u90fd\u6362\u6210\u53e6\u4e00\u4e2a\u6d41\uff0c\u7136\u540e\u628a\u6240\u6709\u6d41\u8fde\u63a5\u6210\u4e00\u4e2a\u6d41\u3002<\/li><\/ul>\n\n\n\n
          \"Stream
          Stream \u6620\u5c04map\/flatMap<\/figcaption><\/figure>\n\n\n\n
          \"Stream
          Stream \u6620\u5c04map\/flatMap<\/figcaption><\/figure>\n\n\n\n
          \u300c\u6848\u4f8b\u4e00\uff1a\u82f1\u6587\u5b57\u7b26\u4e32\u6570\u7ec4\u7684\u5143\u7d20\u5168\u90e8\u6539\u4e3a\u5927\u5199\u3002\u6574\u6570\u6570\u7ec4\u6bcf\u4e2a\u5143\u7d20+3\u3002\u300d<\/strong><\/p>\n\n\n\n
          public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0String[]\u00a0strArr\u00a0=\u00a0{\u00a0\"abcd\",\u00a0\"bcdd\",\u00a0\"defde\",\u00a0\"fTr\"\u00a0};\u00a0\u00a0List<String>\u00a0strList\u00a0=\u00a0Arrays.stream(strArr).map(String::toUpperCase).collect(Collectors.toList());\u00a0\u00a0List<Integer>\u00a0intList\u00a0=\u00a0Arrays.asList(1,\u00a03,\u00a05,\u00a07,\u00a09,\u00a011);\u00a0\u00a0List<Integer>\u00a0intListNew\u00a0=\u00a0intList.stream().map(x\u00a0->\u00a0x\u00a0+\u00a03).collect(Collectors.toList());\u00a0\u00a0System.out.println(\"\u6bcf\u4e2a\u5143\u7d20\u5927\u5199\uff1a\"\u00a0+\u00a0strList);\u00a0\u00a0System.out.println(\"\u6bcf\u4e2a\u5143\u7d20+3\uff1a\"\u00a0+\u00a0intListNew);\u00a0}}<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          \u6bcf\u4e2a\u5143\u7d20\u5927\u5199\uff1a[ABCD, BCDD, DEFDE, FTR]
          \n\u6bcf\u4e2a\u5143\u7d20+3\uff1a[4, 6, 8, 10, 12, 14]\u275e<\/p><\/blockquote>\n\n\n\n
          \u300c\u6848\u4f8b\u4e8c\uff1a\u5c06\u5458\u5de5\u7684\u85aa\u8d44\u5168\u90e8\u589e\u52a01000\u3002\u300d<\/strong><\/p>\n\n\n\n
          public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a024,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Owen\",\u00a09500,\u00a025,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Alisa\",\u00a07900,\u00a026,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0\/\/\u00a0\u4e0d\u6539\u53d8\u539f\u6765\u5458\u5de5\u96c6\u5408\u7684\u65b9\u5f0f\u00a0\u00a0List<Person>\u00a0personListNew\u00a0=\u00a0personList.stream().map(person\u00a0->\u00a0{\u00a0\u00a0\u00a0Person\u00a0personNew\u00a0=\u00a0new\u00a0Person(person.getName(),\u00a00,\u00a00,\u00a0null,\u00a0null);\u00a0\u00a0\u00a0personNew.setSalary(person.getSalary()\u00a0+\u00a010000);\u00a0\u00a0\u00a0return\u00a0personNew;\u00a0\u00a0}).collect(Collectors.toList());\u00a0\u00a0System.out.println(\"\u4e00\u6b21\u6539\u52a8\u524d\uff1a\"\u00a0+\u00a0personList.get(0).getName()\u00a0+\u00a0\"-->\"\u00a0+\u00a0personList.get(0).getSalary());\u00a0\u00a0System.out.println(\"\u4e00\u6b21\u6539\u52a8\u540e\uff1a\"\u00a0+\u00a0personListNew.get(0).getName()\u00a0+\u00a0\"-->\"\u00a0+\u00a0personListNew.get(0).getSalary());\u00a0\u00a0\/\/\u00a0\u6539\u53d8\u539f\u6765\u5458\u5de5\u96c6\u5408\u7684\u65b9\u5f0f\u00a0\u00a0List<Person>\u00a0personListNew2\u00a0=\u00a0personList.stream().map(person\u00a0->\u00a0{\u00a0\u00a0\u00a0person.setSalary(person.getSalary()\u00a0+\u00a010000);\u00a0\u00a0\u00a0return\u00a0person;\u00a0\u00a0}).collect(Collectors.toList());\u00a0\u00a0System.out.println(\"\u4e8c\u6b21\u6539\u52a8\u524d\uff1a\"\u00a0+\u00a0personList.get(0).getName()\u00a0+\u00a0\"-->\"\u00a0+\u00a0personListNew.get(0).getSalary());\u00a0\u00a0System.out.println(\"\u4e8c\u6b21\u6539\u52a8\u540e\uff1a\"\u00a0+\u00a0personListNew2.get(0).getName()\u00a0+\u00a0\"-->\"\u00a0+\u00a0personListNew.get(0).getSalary());\u00a0}}<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          \u4e00\u6b21\u6539\u52a8\u524d\uff1aTom\u2013>8900
          \n\u4e00\u6b21\u6539\u52a8\u540e\uff1aTom\u2013>18900
          \n\u4e8c\u6b21\u6539\u52a8\u524d\uff1aTom\u2013>18900
          \n\u4e8c\u6b21\u6539\u52a8\u540e\uff1aTom\u2013>18900\u275e<\/p><\/blockquote>\n\n\n\n
          \u300c\u6848\u4f8b\u4e09\uff1a\u5c06\u4e24\u4e2a\u5b57\u7b26\u6570\u7ec4\u5408\u5e76\u6210\u4e00\u4e2a\u65b0\u7684\u5b57\u7b26\u6570\u7ec4\u3002\u300d<\/strong><\/p>\n\n\n\n
          public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<String>\u00a0list\u00a0=\u00a0Arrays.asList(\"m,k,l,a\",\u00a0\"1,3,5,7\");\u00a0\u00a0List<String>\u00a0listNew\u00a0=\u00a0list.stream().flatMap(s\u00a0->\u00a0{\u00a0\u00a0\u00a0\/\/\u00a0\u5c06\u6bcf\u4e2a\u5143\u7d20\u8f6c\u6362\u6210\u4e00\u4e2astream\u00a0\u00a0\u00a0String[]\u00a0split\u00a0=\u00a0s.split(\",\");\u00a0\u00a0\u00a0Stream<String>\u00a0s2\u00a0=\u00a0Arrays.stream(split);\u00a0\u00a0\u00a0return\u00a0s2;\u00a0\u00a0}).collect(Collectors.toList());\u00a0\u00a0System.out.println(\"\u5904\u7406\u524d\u7684\u96c6\u5408\uff1a\"\u00a0+\u00a0list);\u00a0\u00a0System.out.println(\"\u5904\u7406\u540e\u7684\u96c6\u5408\uff1a\"\u00a0+\u00a0listNew);\u00a0}}<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          \u5904\u7406\u524d\u7684\u96c6\u5408\uff1a[m-k-l-a, 1-3-5]
          \n\u5904\u7406\u540e\u7684\u96c6\u5408\uff1a[m, k, l, a, 1, 3, 5]\u275e<\/p><\/blockquote>\n\n\n\n
          3.5 \u5f52\u7ea6(reduce)<\/h2>\n\n\n\n
          \u5f52\u7ea6\uff0c\u4e5f\u79f0\u7f29\u51cf\uff0c\u987e\u540d\u601d\u4e49\uff0c\u662f\u628a\u4e00\u4e2a\u6d41\u7f29\u51cf\u6210\u4e00\u4e2a\u503c\uff0c\u80fd\u5b9e\u73b0\u5bf9\u96c6\u5408\u6c42\u548c\u3001\u6c42\u4e58\u79ef\u548c\u6c42\u6700\u503c\u64cd\u4f5c\u3002<\/p>\n\n\n\n
          \"Stream\u5f52\u7ea6reduce\"
          Stream\u5f52\u7ea6reduce<\/figcaption><\/figure>\n\n\n\n
          \u300c\u6848\u4f8b\u4e00\uff1a\u6c42Integer<\/code>\u96c6\u5408\u7684\u5143\u7d20\u4e4b\u548c\u3001\u4e58\u79ef\u548c\u6700\u5927\u503c\u3002\u300d<\/strong><\/p>\n\n\n\n
          public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Integer>\u00a0list\u00a0=\u00a0Arrays.asList(1,\u00a03,\u00a02,\u00a08,\u00a011,\u00a04);\u00a0\u00a0\/\/\u00a0\u6c42\u548c\u65b9\u5f0f1\u00a0\u00a0Optional<Integer>\u00a0sum\u00a0=\u00a0list.stream().reduce((x,\u00a0y)\u00a0->\u00a0x\u00a0+\u00a0y);\u00a0\u00a0\/\/\u00a0\u6c42\u548c\u65b9\u5f0f2\u00a0\u00a0Optional<Integer>\u00a0sum2\u00a0=\u00a0list.stream().reduce(Integer::sum);\u00a0\u00a0\/\/\u00a0\u6c42\u548c\u65b9\u5f0f3\u00a0\u00a0Integer\u00a0sum3\u00a0=\u00a0list.stream().reduce(0,\u00a0Integer::sum);\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u6c42\u4e58\u79ef\u00a0\u00a0Optional<Integer>\u00a0product\u00a0=\u00a0list.stream().reduce((x,\u00a0y)\u00a0->\u00a0x\u00a0*\u00a0y);\u00a0\u00a0\/\/\u00a0\u6c42\u6700\u5927\u503c\u65b9\u5f0f1\u00a0\u00a0Optional<Integer>\u00a0max\u00a0=\u00a0list.stream().reduce((x,\u00a0y)\u00a0->\u00a0x\u00a0>\u00a0y\u00a0?\u00a0x\u00a0:\u00a0y);\u00a0\u00a0\/\/\u00a0\u6c42\u6700\u5927\u503c\u5199\u6cd52\u00a0\u00a0Integer\u00a0max2\u00a0=\u00a0list.stream().reduce(1,\u00a0Integer::max);\u00a0\u00a0System.out.println(\"list\u6c42\u548c\uff1a\"\u00a0+\u00a0sum.get()\u00a0+\u00a0\",\"\u00a0+\u00a0sum2.get()\u00a0+\u00a0\",\"\u00a0+\u00a0sum3);\u00a0\u00a0System.out.println(\"list\u6c42\u79ef\uff1a\"\u00a0+\u00a0product.get());\u00a0\u00a0System.out.println(\"list\u6c42\u548c\uff1a\"\u00a0+\u00a0max.get()\u00a0+\u00a0\",\"\u00a0+\u00a0max2);\u00a0}}<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          list\u6c42\u548c\uff1a29,29,29
          \nlist\u6c42\u79ef\uff1a2112
          \nlist\u6c42\u548c\uff1a11,11\u275e<\/p><\/blockquote>\n\n\n\n
          \u300c\u6848\u4f8b\u4e8c\uff1a\u6c42\u6240\u6709\u5458\u5de5\u7684\u5de5\u8d44\u4e4b\u548c\u548c\u6700\u9ad8\u5de5\u8d44\u3002\u300d<\/strong><\/p>\n\n\n\n
          public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a024,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Owen\",\u00a09500,\u00a025,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Alisa\",\u00a07900,\u00a026,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0\/\/\u00a0\u6c42\u5de5\u8d44\u4e4b\u548c\u65b9\u5f0f1\uff1a\u00a0\u00a0Optional<Integer>\u00a0sumSalary\u00a0=\u00a0personList.stream().map(Person::getSalary).reduce(Integer::sum);\u00a0\u00a0\/\/\u00a0\u6c42\u5de5\u8d44\u4e4b\u548c\u65b9\u5f0f2\uff1a\u00a0\u00a0Integer\u00a0sumSalary2\u00a0=\u00a0personList.stream().reduce(0,\u00a0(sum,\u00a0p)\u00a0->\u00a0sum\u00a0+=\u00a0p.getSalary(),\u00a0\u00a0\u00a0\u00a0(sum1,\u00a0sum2)\u00a0->\u00a0sum1\u00a0+\u00a0sum2);\u00a0\u00a0\/\/\u00a0\u6c42\u5de5\u8d44\u4e4b\u548c\u65b9\u5f0f3\uff1a\u00a0\u00a0Integer\u00a0sumSalary3\u00a0=\u00a0personList.stream().reduce(0,\u00a0(sum,\u00a0p)\u00a0->\u00a0sum\u00a0+=\u00a0p.getSalary(),\u00a0Integer::sum);\u00a0\u00a0\/\/\u00a0\u6c42\u6700\u9ad8\u5de5\u8d44\u65b9\u5f0f1\uff1a\u00a0\u00a0Integer\u00a0maxSalary\u00a0=\u00a0personList.stream().reduce(0,\u00a0(max,\u00a0p)\u00a0->\u00a0max\u00a0>\u00a0p.getSalary()\u00a0?\u00a0max\u00a0:\u00a0p.getSalary(),\u00a0\u00a0\u00a0\u00a0Integer::max);\u00a0\u00a0\/\/\u00a0\u6c42\u6700\u9ad8\u5de5\u8d44\u65b9\u5f0f2\uff1a\u00a0\u00a0Integer\u00a0maxSalary2\u00a0=\u00a0personList.stream().reduce(0,\u00a0(max,\u00a0p)\u00a0->\u00a0max\u00a0>\u00a0p.getSalary()\u00a0?\u00a0max\u00a0:\u00a0p.getSalary(),\u00a0\u00a0\u00a0\u00a0(max1,\u00a0max2)\u00a0->\u00a0max1\u00a0>\u00a0max2\u00a0?\u00a0max1\u00a0:\u00a0max2);\u00a0\u00a0System.out.println(\"\u5de5\u8d44\u4e4b\u548c\uff1a\"\u00a0+\u00a0sumSalary.get()\u00a0+\u00a0\",\"\u00a0+\u00a0sumSalary2\u00a0+\u00a0\",\"\u00a0+\u00a0sumSalary3);\u00a0\u00a0System.out.println(\"\u6700\u9ad8\u5de5\u8d44\uff1a\"\u00a0+\u00a0maxSalary\u00a0+\u00a0\",\"\u00a0+\u00a0maxSalary2);\u00a0}}<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          \u5de5\u8d44\u4e4b\u548c\uff1a49300,49300,49300
          \n\u6700\u9ad8\u5de5\u8d44\uff1a9500,9500\u275e<\/p><\/blockquote>\n\n\n\n
          3.6 \u6536\u96c6(collect)<\/h2>\n\n\n\n
          collect<\/code>\uff0c\u6536\u96c6\uff0c\u53ef\u4ee5\u8bf4\u662f\u5185\u5bb9\u6700\u7e41\u591a\u3001\u529f\u80fd\u6700\u4e30\u5bcc\u7684\u90e8\u5206\u4e86\u3002\u4ece\u5b57\u9762\u4e0a\u53bb\u7406\u89e3\uff0c\u5c31\u662f\u628a\u4e00\u4e2a\u6d41\u6536\u96c6\u8d77\u6765\uff0c\u6700\u7ec8\u53ef\u4ee5\u662f\u6536\u96c6\u6210\u4e00\u4e2a\u503c\u4e5f\u53ef\u4ee5\u6536\u96c6\u6210\u4e00\u4e2a\u65b0\u7684\u96c6\u5408\u3002<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          collect<\/code>\u4e3b\u8981\u4f9d\u8d56java.util.stream.Collectors<\/code>\u7c7b\u5185\u7f6e\u7684\u9759\u6001\u65b9\u6cd5\u3002\u275e<\/p><\/blockquote>\n\n\n\n
          3.6.1 \u5f52\u96c6(toList\/toSet\/toMap)<\/h3>\n\n\n\n
          \u56e0\u4e3a\u6d41\u4e0d\u5b58\u50a8\u6570\u636e\uff0c\u90a3\u4e48\u5728\u6d41\u4e2d\u7684\u6570\u636e\u5b8c\u6210\u5904\u7406\u540e\uff0c\u9700\u8981\u5c06\u6d41\u4e2d\u7684\u6570\u636e\u91cd\u65b0\u5f52\u96c6\u5230\u65b0\u7684\u96c6\u5408\u91cc\u3002toList<\/code>\u3001toSet<\/code>\u548ctoMap<\/code>\u6bd4\u8f83\u5e38\u7528\uff0c\u53e6\u5916\u8fd8\u6709toCollection<\/code>\u3001toConcurrentMap<\/code>\u7b49\u590d\u6742\u4e00\u4e9b\u7684\u7528\u6cd5\u3002<\/p>\n\n\n\n
          \u4e0b\u9762\u7528\u4e00\u4e2a\u6848\u4f8b\u6f14\u793atoList<\/code>\u3001toSet<\/code>\u548ctoMap<\/code>\uff1a<\/p>\n\n\n\n
          public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Integer>\u00a0list\u00a0=\u00a0Arrays.asList(1,\u00a06,\u00a03,\u00a04,\u00a06,\u00a07,\u00a09,\u00a06,\u00a020);\u00a0\u00a0List<Integer>\u00a0listNew\u00a0=\u00a0list.stream().filter(x\u00a0->\u00a0x\u00a0%\u00a02\u00a0==\u00a00).collect(Collectors.toList());\u00a0\u00a0Set<Integer>\u00a0set\u00a0=\u00a0list.stream().filter(x\u00a0->\u00a0x\u00a0%\u00a02\u00a0==\u00a00).collect(Collectors.toSet());\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a024,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0\u00a0\u00a0Map<?,\u00a0Person>\u00a0map\u00a0=\u00a0personList.stream().filter(p\u00a0->\u00a0p.getSalary()\u00a0>\u00a08000)\u00a0\u00a0\u00a0\u00a0.collect(Collectors.toMap(Person::getName,\u00a0p\u00a0->\u00a0p));\u00a0\u00a0System.out.println(\"toList:\"\u00a0+\u00a0listNew);\u00a0\u00a0System.out.println(\"toSet:\"\u00a0+\u00a0set);\u00a0\u00a0System.out.println(\"toMap:\"\u00a0+\u00a0map);\u00a0}}<\/code><\/pre>\n\n\n\n
          \u8fd0\u884c\u7ed3\u679c\uff1a<\/p>\n\n\n\n
          \u275d<\/strong><\/p>
          toList\uff1a[6, 4, 6, 6, 20]
          \ntoSet\uff1a[4, 20, 6]
          \ntoMap\uff1a{Tom=mutest.Person@5fd0d5ae, Anni=mutest.Person@2d98a335}\u275e<\/p><\/blockquote>\n\n\n\n
          3.6.2 \u7edf\u8ba1(count\/averaging)<\/h3>\n\n\n\n
          Collectors<\/code>\u63d0\u4f9b\u4e86\u4e00\u7cfb\u5217\u7528\u4e8e\u6570\u636e\u7edf\u8ba1\u7684\u9759\u6001\u65b9\u6cd5\uff1a<\/p>\n\n\n\n
          • \u8ba1\u6570\uff1acount<\/code><\/li>
          • \u5e73\u5747\u503c\uff1aaveragingInt<\/code>\u3001averagingLong<\/code>\u3001averagingDouble<\/code><\/li>
          • \u6700\u503c\uff1amaxBy<\/code>\u3001minBy<\/code><\/li>
          • \u6c42\u548c\uff1asummingInt<\/code>\u3001summingLong<\/code>\u3001summingDouble<\/code><\/li>
          • \u7edf\u8ba1\u4ee5\u4e0a\u6240\u6709\uff1asummarizingInt<\/code>\u3001summarizingLong<\/code>\u3001summarizingDouble<\/code><\/li><\/ul>\n\n\n\n
            \u300c\u6848\u4f8b\uff1a\u7edf\u8ba1\u5458\u5de5\u4eba\u6570\u3001\u5e73\u5747\u5de5\u8d44\u3001\u5de5\u8d44\u603b\u989d\u3001\u6700\u9ad8\u5de5\u8d44\u3002\u300d<\/strong><\/p>\n\n\n\n
            public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0\/\/\u00a0\u6c42\u603b\u6570\u00a0\u00a0Long\u00a0count\u00a0=\u00a0personList.stream().collect(Collectors.counting());\u00a0\u00a0\/\/\u00a0\u6c42\u5e73\u5747\u5de5\u8d44\u00a0\u00a0Double\u00a0average\u00a0=\u00a0personList.stream().collect(Collectors.averagingDouble(Person::getSalary));\u00a0\u00a0\/\/\u00a0\u6c42\u6700\u9ad8\u5de5\u8d44\u00a0\u00a0Optional<Integer>\u00a0max\u00a0=\u00a0personList.stream().map(Person::getSalary).collect(Collectors.maxBy(Integer::compare));\u00a0\u00a0\/\/\u00a0\u6c42\u5de5\u8d44\u4e4b\u548c\u00a0\u00a0Integer\u00a0sum\u00a0=\u00a0personList.stream().collect(Collectors.summingInt(Person::getSalary));\u00a0\u00a0\/\/\u00a0\u4e00\u6b21\u6027\u7edf\u8ba1\u6240\u6709\u4fe1\u606f\u00a0\u00a0DoubleSummaryStatistics\u00a0collect\u00a0=\u00a0personList.stream().collect(Collectors.summarizingDouble(Person::getSalary));\u00a0\u00a0System.out.println(\"\u5458\u5de5\u603b\u6570\uff1a\"\u00a0+\u00a0count);\u00a0\u00a0System.out.println(\"\u5458\u5de5\u5e73\u5747\u5de5\u8d44\uff1a\"\u00a0+\u00a0average);\u00a0\u00a0System.out.println(\"\u5458\u5de5\u5de5\u8d44\u603b\u548c\uff1a\"\u00a0+\u00a0sum);\u00a0\u00a0System.out.println(\"\u5458\u5de5\u5de5\u8d44\u6240\u6709\u7edf\u8ba1\uff1a\"\u00a0+\u00a0collect);\u00a0}}<\/code><\/pre>\n\n\n\n
            \u8fd0\u884c\u7ed3\u679c\uff1a<\/p>\n\n\n\n
            \u275d<\/strong><\/p>
            \u5458\u5de5\u603b\u6570\uff1a3
            \n\u5458\u5de5\u5e73\u5747\u5de5\u8d44\uff1a7900.0
            \n\u5458\u5de5\u5de5\u8d44\u603b\u548c\uff1a23700
            \n\u5458\u5de5\u5de5\u8d44\u6240\u6709\u7edf\u8ba1\uff1aDoubleSummaryStatistics{count=3, sum=23700.000000,min=7000.000000, average=7900.000000, max=8900.000000}\u275e<\/p><\/blockquote>\n\n\n\n
            3.6.3 \u5206\u7ec4(partitioningBy\/groupingBy)<\/h3>\n\n\n\n
            • \u5206\u533a\uff1a\u5c06stream<\/code>\u6309\u6761\u4ef6\u5206\u4e3a\u4e24\u4e2aMap<\/code>\uff0c\u6bd4\u5982\u5458\u5de5\u6309\u85aa\u8d44\u662f\u5426\u9ad8\u4e8e8000\u5206\u4e3a\u4e24\u90e8\u5206\u3002<\/li>
            • \u5206\u7ec4\uff1a\u5c06\u96c6\u5408\u5206\u4e3a\u591a\u4e2aMap\uff0c\u6bd4\u5982\u5458\u5de5\u6309\u6027\u522b\u5206\u7ec4\u3002\u6709\u5355\u7ea7\u5206\u7ec4\u548c\u591a\u7ea7\u5206\u7ec4\u3002<\/li><\/ul>\n\n\n\n
              \"Stream\u5206\u7ec4partitioningBy\/groupingBy\"
              Stream\u5206\u7ec4partitioningBy\/groupingBy<\/figcaption><\/figure>\n\n\n\n
              \u300c\u6848\u4f8b\uff1a\u5c06\u5458\u5de5\u6309\u85aa\u8d44\u662f\u5426\u9ad8\u4e8e8000\u5206\u4e3a\u4e24\u90e8\u5206\uff1b\u5c06\u5458\u5de5\u6309\u6027\u522b\u548c\u5730\u533a\u5206\u7ec4\u300d<\/strong><\/p>\n\n\n\n
              public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Anni\",\u00a08200,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Owen\",\u00a09500,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Alisa\",\u00a07900,\u00a0\"female\",\u00a0\"New\u00a0York\"));\u00a0\u00a0\/\/\u00a0\u5c06\u5458\u5de5\u6309\u85aa\u8d44\u662f\u5426\u9ad8\u4e8e8000\u5206\u7ec4\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Map<Boolean,\u00a0List<Person>>\u00a0part\u00a0=\u00a0personList.stream().collect(Collectors.partitioningBy(x\u00a0->\u00a0x.getSalary()\u00a0>\u00a08000));\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u5c06\u5458\u5de5\u6309\u6027\u522b\u5206\u7ec4\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Map<String,\u00a0List<Person>>\u00a0group\u00a0=\u00a0personList.stream().collect(Collectors.groupingBy(Person::getSex));\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0\u5c06\u5458\u5de5\u5148\u6309\u6027\u522b\u5206\u7ec4\uff0c\u518d\u6309\u5730\u533a\u5206\u7ec4\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Map<String,\u00a0Map<String,\u00a0List<Person>>>\u00a0group2\u00a0=\u00a0personList.stream().collect(Collectors.groupingBy(Person::getSex,\u00a0Collectors.groupingBy(Person::getArea)));\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0System.out.println(\"\u5458\u5de5\u6309\u85aa\u8d44\u662f\u5426\u5927\u4e8e8000\u5206\u7ec4\u60c5\u51b5\uff1a\"\u00a0+\u00a0part);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0System.out.println(\"\u5458\u5de5\u6309\u6027\u522b\u5206\u7ec4\u60c5\u51b5\uff1a\"\u00a0+\u00a0group);\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0System.out.println(\"\u5458\u5de5\u6309\u6027\u522b\u3001\u5730\u533a\uff1a\"\u00a0+\u00a0group2);\u00a0}}<\/code><\/pre>\n\n\n\n
              \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n\n\n\n
              \u5458\u5de5\u6309\u85aa\u8d44\u662f\u5426\u5927\u4e8e8000\u5206\u7ec4\u60c5\u51b5\uff1a{false=[mutest.Person@2d98a335,\u00a0mutest.Person@16b98e56,\u00a0mutest.Person@7ef20235],\u00a0true=[mutest.Person@27d6c5e0,\u00a0mutest.Person@4f3f5b24,\u00a0mutest.Person@15aeb7ab]}\u5458\u5de5\u6309\u6027\u522b\u5206\u7ec4\u60c5\u51b5\uff1a{female=[mutest.Person@16b98e56,\u00a0mutest.Person@4f3f5b24,\u00a0mutest.Person@7ef20235],\u00a0male=[mutest.Person@27d6c5e0,\u00a0mutest.Person@2d98a335,\u00a0mutest.Person@15aeb7ab]}\u5458\u5de5\u6309\u6027\u522b\u3001\u5730\u533a\uff1a{female={New\u00a0York=[mutest.Person@4f3f5b24,\u00a0mutest.Person@7ef20235],\u00a0Washington=[mutest.Person@16b98e56]},\u00a0male={New\u00a0York=[mutest.Person@27d6c5e0,\u00a0mutest.Person@15aeb7ab],\u00a0Washington=[mutest.Person@2d98a335]}}<\/code><\/pre>\n\n\n\n
              3.6.4 \u63a5\u5408(joining)<\/h3>\n\n\n\n
              joining<\/code>\u53ef\u4ee5\u5c06stream\u4e2d\u7684\u5143\u7d20\u7528\u7279\u5b9a\u7684\u8fde\u63a5\u7b26\uff08\u6ca1\u6709\u7684\u8bdd\uff0c\u5219\u76f4\u63a5\u8fde\u63a5\uff09\u8fde\u63a5\u6210\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002<\/p>\n\n\n\n
              public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0String\u00a0names\u00a0=\u00a0personList.stream().map(p\u00a0->\u00a0p.getName()).collect(Collectors.joining(\",\"));\u00a0\u00a0System.out.println(\"\u6240\u6709\u5458\u5de5\u7684\u59d3\u540d\uff1a\"\u00a0+\u00a0names);\u00a0\u00a0List<String>\u00a0list\u00a0=\u00a0Arrays.asList(\"A\",\u00a0\"B\",\u00a0\"C\");\u00a0\u00a0String\u00a0string\u00a0=\u00a0list.stream().collect(Collectors.joining(\"-\"));\u00a0\u00a0System.out.println(\"\u62fc\u63a5\u540e\u7684\u5b57\u7b26\u4e32\uff1a\"\u00a0+\u00a0string);\u00a0}}<\/code><\/pre>\n\n\n\n
              \u8fd0\u884c\u7ed3\u679c\uff1a<\/p>\n\n\n\n
              \u275d<\/strong><\/p>
              \u6240\u6709\u5458\u5de5\u7684\u59d3\u540d\uff1aTom,Jack,Lily
              \n\u62fc\u63a5\u540e\u7684\u5b57\u7b26\u4e32\uff1aA-B-C\u275e<\/p><\/blockquote>\n\n\n\n
              3.6.5 \u5f52\u7ea6(reducing)<\/h3>\n\n\n\n
              Collectors<\/code>\u7c7b\u63d0\u4f9b\u7684reducing<\/code>\u65b9\u6cd5\uff0c\u76f8\u6bd4\u4e8estream<\/code>\u672c\u8eab\u7684reduce<\/code>\u65b9\u6cd5\uff0c\u589e\u52a0\u4e86\u5bf9\u81ea\u5b9a\u4e49\u5f52\u7ea6\u7684\u652f\u6301\u3002<\/p>\n\n\n\n
              public\u00a0class\u00a0StreamTest\u00a0{\u00a0public\u00a0static\u00a0void\u00a0main(String[]\u00a0args)\u00a0{\u00a0\u00a0List<Person>\u00a0personList\u00a0=\u00a0new\u00a0ArrayList<Person>();\u00a0\u00a0personList.add(new\u00a0Person(\"Tom\",\u00a08900,\u00a023,\u00a0\"male\",\u00a0\"New\u00a0York\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Jack\",\u00a07000,\u00a025,\u00a0\"male\",\u00a0\"Washington\"));\u00a0\u00a0personList.add(new\u00a0Person(\"Lily\",\u00a07800,\u00a021,\u00a0\"female\",\u00a0\"Washington\"));\u00a0\u00a0\/\/\u00a0\u6bcf\u4e2a\u5458\u5de5\u51cf\u53bb\u8d77\u5f81\u70b9\u540e\u7684\u85aa\u8d44\u4e4b\u548c\uff08\u8fd9\u4e2a\u4f8b\u5b50\u5e76\u4e0d\u4e25\u8c28\uff0c\u4f46\u4e00\u65f6\u6ca1\u60f3\u5230\u597d\u7684\u4f8b\u5b50\uff09\u00a0\u00a0Integer\u00a0sum\u00a0=\u00a0personList.stream().collect(Collectors.reducing(0,\u00a0Person::getSalary,\u00a0(i,\u00a0j)\u00a0->\u00a0(i\u00a0+\u00a0j\u00a0-\u00a05000)));\u00a0\u00a0System.out.println(\"\u5458\u5de5\u6263\u7a0e\u85aa\u8d44\u603b\u548c\uff1a\"\u00a0+\u00a0sum);\u00a0\u00a0\/\/\u00a0stream\u7684reduce\u00a0\u00a0Optional<Integer>\u00a0sum2\u00a0=\u00a0personList.stream().map(Person::getSalary).reduce(Integer::sum);\u00a0\u00a0System.out.println(\"\u5458\u5de5\u85aa\u8d44\u603b\u548c\uff1a\"\u00a0+\u00a0sum2.get());\u00a0}}<\/code><\/pre>\n\n\n\n
              \u8fd0\u884c\u7ed3\u679c\uff1a<\/p>\n\n\n\n
              \u275d<\/strong><\/p>
              \u5458\u5de5\u6263\u7a0e\u85aa\u8d44\u603b\u548c\uff1a8700
              \n\u5458\u5de5\u85aa\u8d44\u603b\u548c\uff1a23700\u275e<\/p><\/blockquote>\n\n\n\n
              3.7 \u6392\u5e8f(sorted)<\/h2>\n\n\n\n
              sorted\uff0c\u4e2d\u95f4\u64cd\u4f5c\u3002\u6709\u4e24\u79cd\u6392\u5e8f\uff1a<\/p>\n\n\n\n