As there seems to be currently no ready-to-go example for an Android application communicating with a GRPC server which doesn't involve setting up a boatload of tools we decided to create this simple demo project which contains a simple GRPC Java server and a matching Android client.

The setup contains working code generation so feel free to change the proto file in lib_hello_grpc. Upon the next build the necessary classes are generated by the gradle grpc plugin. You'll just have to adapt the server and client code to the newly generated GRPC java classes. The compiler will point you to the locations you have to change by means of compilitation errors.

It is advisable to clean the lib_hello_grpc module by calling ./gradlew :lib_hello_grpc:clean after having removed or changed the name of a service or a message. This will remove all stale generated classes and prevent compilation errors within the other generated classes.

The following documentation assumes that you've installed Android Studio. Import the project via gradle.

By default the server runs on port 8080, but you may change that via command line arguments or directly in the code.

Run the server from Android Studio by right-clicking the Server.java in the lib_hello_grpc module. This also creates a suitable run configuration which you can use to run the server again later. After importing the project here will be errors which are automatically resolved during the first build via code generation. Make sure, that only one server instance runs at a time (at least if you attempt to use the same port).

Incoming requests are logged on stdout.

While importing the project to Android Studio via gradle the IDE automatically generates a run configuration for the app which you can use to install it on your device or emulator.

In the app first type in the hostname and the port of your server. Then click on the HELLO SERVER! button to execute a request against your GRPC server instance. In case of success the server will reply with Hello Android.

If you did everything correctly it should look something like this:

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