In order to run the examples simply execute one of the gradle tasks routeGuideServer, routeGuideClient, helloWorldServer, or helloWorldClient.
For example, say you want to play around with the route guide examples. First you want to start the server and then have the client connect to it and let the good times roll.
Assuming you are in the grpc-java root folder you would first start the route guide server by running
$ ./gradlew :grpc-examples:routeGuideServer
and in a different terminal window then run the route guide client by typing
$ ./gradlew :grpc-examples:routeGuideClient
That's it!
Please refer to [Getting Started Guide for Java] (https://github.com/grpc/grpc-common/blob/master/java/javatutorial.md) for more information.