Due to the official akka-quickstart-java is no longer suppport java8, but I have to implement it with java8. So I make some modifications to pom file and Greeter file, so that the project can be successfully runned with java 8 and akka 2.8.5 (the last akka version supporting java 8).
Here is the official repo: https://github.com/akka/akka-quickstart-java.g8.
Hope it will be helpful for akka beginners.