Alpine is the base image which is based on Alpine Linux, a very compact Linux distribution. So, node:12.2.0-alpine is a Alpine Linux image with node 12.2.0 installed.

For the latest Alpine based image you can simply do node:alpine. If you want latest but not specifically Alpine you can do node:latest, that image will be based on stretch which is a Debian distribution.

You can find a full list of all supported tags here: https://hub.docker.com/_/node/

First you must update the package list with apt-get update, then you can install openjdk-8. openjdk-11 isn't available with that distribution of node. I used docker run -it node:12 /bin/bash to see what there was,

FROM node:12
RUN apt-get update && apt-get install -y openjdk-8-jdk

For example,

$ cat Dockerfile                                         
FROM node:12
RUN apt-get update && apt-get install -y openjdk-8-jdk
$ docker build --tag mynode:1.0 .
$ docker run -it mynode:1.0 /bin/bash                                    
root@d70858199dd1:/# java -version
openjdk version "1.8.0_265"
OpenJDK Runtime Environment (build 1.8.0_265-8u265-b01-0+deb9u1-b01)
OpenJDK 64-Bit Server VM (build 25.265-b01, mixed mode)
root@d70858199dd1:/# javac -version
javac 1.8.0_265
root@d70858199dd1:/#

If you really do need Java 11, there are multiple ways and places to get openjdk-11. One is bell-sw. For example,

$ cat Dockerfile
FROM node:12
RUN apt-get update && apt-get install -y libasound2 libxtst6
RUN wget https://download.bell-sw.com/java/11.0.7+10/bellsoft-jdk11.0.7+10-linux-amd64.deb && \
    apt install ./bellsoft-jdk11.0.7+10-linux-amd64.deb
$ docker build --tag mynode:1.1 .
$ docker run -it mynode:1.1 /bin/bash
root@37771ce98727:/# java -version
openjdk version "11.0.7" 2020-04-14 LTS
OpenJDK Runtime Environment (build 11.0.7+10-LTS)
OpenJDK 64-Bit Server VM (build 11.0.7+10-LTS, mixed mode)
root@37771ce98727:/# javac -version
javac 11.0.7