simomat/streamjoin: Java 8 Stream joins
https://github.com/simomat/streamjoin
Common SQL Clauses and Their Equivalents in Java 8 Streams – Java, SQL and jOOQ.
https://blog.jooq.org/2015/08/13/common-sql-clauses-and-their-equivalents-in-java-8-streams/
10 ways to Join two Lists in Java - Techie Delight
https://www.techiedelight.com/join-two-lists-java/
"Left join" of two different Java objects - Stack Overflow
https://stackoverflow.com/questions/25593733/left-join-of-two-different-java-objects
(2 条消息) 利用Java8 stream如何实现left join操作？ - 知乎
https://www.zhihu.com/question/345344979
Java8 - 更优雅的字符串连接(join)收集器 Collectors.joining_java_Zebe-CSDN博客
https://blog.csdn.net/zebe1989/article/details/83054037
Flink流计算编程：双流中实现Inner Join、Left Join与Right Join_大数据_lmalds的专栏-CSDN博客
https://blog.csdn.net/lmalds/article/details/52085794
Java Stream Api INNER JOIN Two Lists - Stack Overflow
https://stackoverflow.com/questions/36913083/java-stream-api-inner-join-two-lists
Common SQL Clauses and Their Equivalents in Java 8 Streams – Java, SQL and jOOQ.
https://blog.jooq.org/2015/08/13/common-sql-clauses-and-their-equivalents-in-java-8-streams/
Stream (Java Platform SE 8 )
https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#collect-java.util.stream.Collector-
jOOQ: The easiest way to write SQL in Java
https://www.jooq.org/
Java8 - 更优雅的字符串连接(join)收集器 Collectors.joining_java_Zebe-CSDN博客
https://blog.csdn.net/zebe1989/article/details/83054037
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Java 8 Streams map() 示例_java_程序猿_三产-CSDN博客
https://blog.csdn.net/sanchan/article/details/70753645
Working With Maps Using Streams | Baeldung
https://www.baeldung.com/java-maps-streams
Convert a Stream to HashMap in Java 8 – StaticReference
https://www.staticreference.com/convert-a-stream-to-hashmap-in-java-8/
Hashmap with Streams in Java 8 Streams to collect value of Map - Stack Overflow
https://stackoverflow.com/questions/29625529/hashmap-with-streams-in-java-8-streams-to-collect-value-of-map
使用Java8 Stream API对Map按键或值进行排序 - 字母哥博客 - 博客园
https://www.cnblogs.com/zimug/p/11781375.html
Initialize a HashMap in Java | Baeldung
https://www.baeldung.com/java-initialize-hashmap
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使用Java8 合并List<Map<String,Object>>为一个Map? - SegmentFault 思否
https://segmentfault.com/q/1010000010380854
scala中的flatMap详解? - 知乎
https://www.zhihu.com/question/34548588?sort=created
Java8 Stream使用flatMap合并List_java_卓立的博客-CSDN博客
https://blog.csdn.net/weixin_41835612/article/details/83713891
Scala入门：map操作和flatMap操作_厦大数据库实验室博客
http://dblab.xmu.edu.cn/blog/961-2/
guava （三） 集合工具类_Java_chiperfect的专栏-CSDN博客
https://blog.csdn.net/chiperfect/article/details/47093189
[Google Guava] 2.3-强大的集合工具类：java.util.Collections中未包含的集合工具 | 并发编程网 – ifeve.com
http://ifeve.com/google-guava-collectionutilities/