Search for java on Docker Hub and the official image is the top hit.
You might start by downloading the Java package:
docker pull java
Run a container to check the Java version:
docker run java java -version
And then the JRE build for Alpine is the smallest:
docker pull java:8-jre-alpine
docker image ls java
Latest is 640MB; 8 JRE is 100MB but both 5 years old...
The official Java page on Docker Hub is actually a redirect to the OpenJDK package, which is an open-source Java runtime.
But the java package is not the same as openjdk - and you should use openjdk because it's more up-to-date:
docker pull openjdk
docker pull openjdk:8-jre-alpine
The default image tag is much more recent, and both images are smaller:
docker image ls openjdk
Back to the exercises.