gcj-aarch64-linux-gnu software package provides GNU Java compiler (based on GCC) for the arm64 architecture, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gcj-aarch64-linux-gnu
gcj-aarch64-linux-gnu is installed in your system.
Make ensure the gcj-aarch64-linux-gnu package were installed using the commands given below,
$ sudo dpkg-query -l | grep gcj-aarch64-linux-gnu *
You will get with gcj-aarch64-linux-gnu package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Development |
| Package | gcj-aarch64-linux-gnu |
| Version | 4:5.3.1-1ubuntu1 |
| Description | GNU Java compiler (based on GCC) for the arm64 architecture |
| Sub Section | Devel |