java 8、9、10、11新特性學習

1. java8：https://www.runoob.com/java/java8-streams.html
2. java9：https://www.runoob.com/java/java9-new-features.html
3. java10：https://www.ibm.com/developerworks/cn/java/the-new-features-of-Java-10/index.html
4. java11：https://www.ibm.com/developerworks/cn/java/the-new-features-of-Java-11/index.html
5. java12：https://www.ibm.com/developerworks/cn/java/the-new-features-of-Java-12/index.html