http://blog.didispace.com/books/java8-tutorial/ch1.html
https://www.mkyong.com/tutorials/java-8-tutorials/
https://colobu.com/2016/03/02/Java-Stream/
https://www.mkyong.com/java8/java-8-lambda-comparator-example/
https://www.cnblogs.com/CarpenterLee/p/6545321.html
https://www.runoob.com/java/java8-new-features.html