Need to install Java runtime in Ubuntu Core 16

Need to install java runtime in Ubuntu Core 16. Do we already have a snap for the same which I can use

If you want to run your Java application on UC16 then it is expected that you simply package it as a snap with all dependencies included. The docs should provide some guidance https://snapcraft.io/docs/java-applications

There is a jre snap that provides a content interface:

$ snap info java-jre-ondra
name:      java-jre-ondra
summary:   java 8 runtime snap
publisher: Ondrej Kubik (ondra)
store-url: https://snapcraft.io/java-jre-ondra
contact:   ondrej.kubik@canonical.com
license:   Proprietary
description: |
  Java 8 run time snap, this snap is intented to be used by other snap_fileset
  using content interface
snap-id: YZzHsom6pmxxllpYBUTxrxWb4tYJ95EW
channels:
  latest/stable:    –                               
  latest/candidate: –                               
  latest/beta:      –                               
  latest/edge:      1.8.0-252 2020-06-11 (36) 132MB -
$

It says that the license is proprietary. Is is not opensource. Sorry for asking this as I am new to this community and Ubuntu Core

Well, the snap has a contact field … i know it is originally based on the deb package, perhaps @ondra can elaborate (being the maintainer)

It says proprietary because I have not filed in license info and I think this is default value then.
Java runtime is Zulu (https://www.azul.com) so the license will be according to what is license of Zulu.
If check snap content you will see there license file
$ less /snap/java-jre-ondra/current/LICENSE_ZULU
There you will see: The GNU General Public License (GPL)

@ondra Is this snap compatible with Ubuntu Core 16. Also when I try to run the below command, it give me a error attached:

sudo snap install java-jre-ondra

For removing I believe I just need to run the below command:

sudo snap remove java-jre-ondra

yes, you can install snap on both Core16 and Core18 devices
I have only published to the edge channel as this is more experimental snap how to package Zulu as snap. As in most cases you would actually bungle jre into your snap.
This enables use cases when there are multiple java snaps and you would have potentially multiple identical jres on same machine, so you would share jre over content interface