The eos4j sample application is designed to show a basic use case of eos4j. It's built using LibGDX for convenience; this isn't necessary to use eos4j.
All the interesting bits are in EpicPlatformManager.java. The rest is
really just application and UI code that isn't particularly relevant to eos4j.
You'll need to do a few things before you're able to run the app and start messing with it.
You'll need an application set up on the EOS Portal. You'll need to grab your Product ID,
Sandbox ID, Deployment ID, Client ID and Client Secret. Populate the fields in
EpicVars.java with
these values.
For legal reasons eos4j does not include the EOS SDK itself; you'll need to
provide that. Copy the SDK/ directory provided by Epic to desktop/EOS/SDK.
The eos4j sample uses Developer Auth as its login mechanism, using the
Dev Auth Tool provided in the SDK. You should run it on localhost:1234,
with the credential name eos4j.
To use the stats, achievements, leaderboards and so on, you'll need to set these up in your EOS developer portal. The sample is built in such a way that you can use whatever values for these you like; if you want something quick, Epic provide a template.
The sample app uses Gradle as its build system, and includes a Gradle wrapper for your convenience. To run the app, simply execute:
# Linux / macOS
./gradlew desktop:run
# Windows
gradlew.bat desktop:run