How to send a message to an Akka Actor and wait for a reply

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 13.10, “How to send a message to an Akka Actor and wait for a reply.”


You have one actor that needs to ask another actor for some information, and needs an immediate reply. (The first actor can’t continue without the information from the second actor.)


Use the ? or ask methods to send a message to an Akka actor and wait for a reply, as demonstrated in the following example:

What Twitter icons mean

Twitter icons meaning: I may be the only one on the planet who doesn't understand the meaning of the current Twitter icons, but really, I don't understand most of them. A Twitter reply icon is an empty ballon? The media icon I kinda get, but the Twitter geo pin icon I don't get. (Maybe I don't work with geo tags and geographic locations much, but I can think of a few million people who also don't.)