Open built-in Terminal from the Android Studio or IntelliJ IDEA.
If you prefer, use the terminal app on your computer.
In the terminal window, cd to the project root directory dl4j-examples if not already in.
And then type ./gradlew NameOfExampleToRun to run the examples as shown below.
(you can use IDE's run-configuration green run button, if you like.)
MLPMnistSingleLayerExample
./gradlew MLPMnistSingleLayerExample
MLPMnistTwoLayerExample
./gradlew MLPMnistTwoLayerExample
etc.