Building OpenJDK 9 on Ubuntu

build_jdk_9.sh

bash ./configure 
make all

clone_sources.sh

hg clone http://hg.openjdk.java.net/jdk9/jdk9 OpenJDK9
cd OpenJDK9
bash ./get_source.sh

env_setup.sh

make -version
unset JAVA_HOME
export LANG=C
export PATH="/usr/lib/jvm/java-8-openjdk-amd64/bin:${PATH}"

install_jdk_8.sh

sudo apt-get install openjdk-8-jdk
java -version

install_libs.sh

# X11 libraries
sudo apt-get install libx11-dev libxext-dev
sudo apt-get install libxrender-dev libxtst-dev libxt-dev
# ALSA library
sudo apt-get install libasound2-dev
# FreeType 2 font engine
sudo apt-get install libfreetype6-dev
# CUPS library
sudo apt-get install libcups2-dev

install_mercurial.sh

sudo apt-get install mercurial

verify_java_9.sh

build/linux-x86_64-normal-server-release/images/j2sdk-image/bin/java -version  
openjdk version "1.9.0-internal"  
OpenJDK Runtime Environment (build 1.9.0-internal-artur_2014_11_16_19_39-b00)  
OpenJDK 64-Bit Server VM (build 1.9.0-internal-artur_2014_11_16_19_39-b00, mixed mode)